[
  {
    "id": "making-conversation",
    "title": "Making conversation（让对话不冷场）",
    "cefr": "A2",
    "difficulty": 1,
    "summary": "right / OK / so 组织话题，I see / Right 表示在听，Well / Let me think 争取思考时间——三类小工具让对话顺畅不断线。",
    "md": "# Making conversation（让对话不冷场）\n\n## ① 目标·导入\n\n学会三类「对话润滑剂」：组织词、回应词、拖延短语，让英语对话不冷场。\n\n## ② 规则讲解\n\n英语对话里有三类小工具。①**组织词**（organizing words）：用来开场、接话或收尾——`right` 表示「好了，注意听」，`OK` 表示「收到、明白」，`so` 表示「那么，总结一下」。②**回应词**（backchanneling）：听别人说话时，用 `Right. / I see. / That's true.` 表示你在认真听。③**拖延短语**（stalling）：遇到难题需要时间想，用 `Well… / Let me think… / That's a good question.` 先开口，不冷场。\n\n```text\n开场/转折：Right, … / OK, … / So, …\n表示在听：Right. / I see. / That's true.\n争取时间：Well… / Let me think… / That's a good question.\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **Right, let's start the meeting.** | 好了，我们开始开会吧。 |\n| **I see. That's really interesting.** | 我明白了，真有意思。 |\n| **Well, let me think… I'd say blue.** | 嗯，让我想想……我觉得是蓝色。 |\n\n## ④ 易错·对比\n\n**常见错误：卡住时一直沉默或只说 um…**\n\n- ❌ 被问住了就沉默不说话。\n- ✅ 先说 `Well… Let me think…`，边说边想。\n- 原因：英语对话习惯用短语「占住话头」，给自己争取思考时间，也显得有礼貌。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"想提醒大家「好了，我们开始吧」，可以说：\",\n      \"options\": [\n        \"Right, let's start.\",\n        \"I see.\",\n        \"Let me think.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"Right 常用来引起注意、宣布开始。I see 是「我明白了」，Let me think 是拖延短语。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"朋友在讲话，你想表示自己在认真听，最好说：\",\n      \"options\": [\n        \"Shut up.\",\n        \"I see. That's interesting.\",\n        \"Goodbye.\"\n      ],\n      \"answer\": 1,\n      \"explain\": \"I see. / Right. / That's true. 都是回应词（backchanneling），表示你在听而且感兴趣。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"被问到一个难回答的问题，需要先想想，可以先说：\",\n      \"options\": [\n        \"Well, that's a good question. Let me think…\",\n        \"I don't know. Bye.\",\n        \"You must wait a long time.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"用 stalling 拖延短语先接住问题，争取思考时间，对话不会冷场。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nright / OK / so 组织话题，I see / Right 表示在听，Well / Let me think 争取思考时间——三类小工具让对话顺畅不断线。\n"
  },
  {
    "id": "adverbs-of-frequency",
    "title": "Adverbs of frequency（频率副词）",
    "cefr": "A1",
    "difficulty": 1,
    "summary": "always / usually / often / sometimes / never 从高到低表示频率，放在实义动词前、be 动词后；never 本身否定，不再加 not。",
    "md": "# Adverbs of frequency（频率副词）\n\n## ① 目标·导入\n\n学会用 always、usually、often、sometimes、never 说清「多久做一次」。\n\n## ② 规则讲解\n\n频率副词按「频繁程度」从高到低排：**always**（总是）> **usually**（通常）> **often**（经常）> **sometimes**（有时）> **never**（从不）。位置有口诀：**实义动词前，be 动词后**。问频率用 How often…?\n\n```text\n主语 + 频率副词 + 实义动词   I often read books.\n主语 + be + 频率副词          She is always happy.\n提问：How often do you …?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I always get up at seven.** | 我总是七点起床。 |\n| **She is often late for class.** | 她上课经常迟到。 |\n| **We sometimes play football after school.** | 我们放学后有时踢足球。 |\n\n## ④ 易错·对比\n\n**常见错误：never 和 not 一起用**\n\n- ❌ I don't never eat candy.\n- ✅ I never eat candy.\n- 原因：never 本身已经表示「从不、不」，再加 not 就重复否定了。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我通常步行上学。」= I ___ walk to school.\",\n      \"options\": [\n        \"usually\",\n        \"never\",\n        \"be\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"usually 表示「通常」，放在实义动词 walk 前面。never 是「从不」，意思不对；be 不是频率副词。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"频率副词在句子里一般放在哪里？\",\n      \"options\": [\n        \"实义动词前，be 动词后\",\n        \"一定在句首\",\n        \"一定在句末\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"口诀：实义动词前（I often read），be 动词后（She is always happy）。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"下面哪组是按频率从高到低排列的？\",\n      \"options\": [\n        \"always > usually > often\",\n        \"often > always > usually\",\n        \"usually > always > often\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"always（总是）最高，然后 usually（通常）、often（经常）、sometimes（有时）、never（从不）。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nalways / usually / often / sometimes / never 从高到低表示频率，放在实义动词前、be 动词后；never 本身否定，不再加 not。\n"
  },
  {
    "id": "so-and-such",
    "title": "“So” and “such”（强调的 so 与 such）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "so + 形容词/副词，such +（a/an）+ 名词；表示「如此……以致……」时后面接 that 从句。",
    "md": "# “So” and “such”（强调的 so 与 such）\n\n## ① 目标·导入\n\n学会用 so 和 such 加强语气，并分清两者的搭配。\n\n## ② 规则讲解\n\n**so** 放在形容词或副词前加强语气：so big / so fast。**such** 放在名词（或「形容词 + 名词」）前加强语气：such a day / such a cold day。表示「如此……以致……」时，两者后面都可以接 **that** 从句。\n\n```text\nso + 形容词/副词 (+ that…)\nsuch (+ a/an) + (形容词) + 名词 (+ that…)\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **The bag is so heavy.** | 这个包太重了。 |\n| **It was such a cold day.** | 那是非常冷的一天。 |\n| **He ran so fast that he won the race.** | 他跑得太快了，结果赢了比赛。 |\n\n## ④ 易错·对比\n\n**常见错误：名词前误用 so**\n\n- ❌ It was so nice day.\n- ✅ It was such a nice day.\n- 原因：中心词是名词 day，强调名词要用 such；so 只直接修饰形容词/副词。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"It was ___ a funny film. Everyone laughed.\",\n      \"options\": [\n        \"such\",\n        \"so\",\n        \"very\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"a funny film 是名词短语，强调名词用 such a + 形容词 + 名词。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"The soup is ___ hot. I can't drink it.\",\n      \"options\": [\n        \"so\",\n        \"such\",\n        \"such a\"\n      ],\n      \"answer\": 1,\n      \"explain\": \"hot 是形容词，形容词前用 so：so hot。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"It was such a big dog.\",\n        \"It was so a big dog.\",\n        \"It was such big dog.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"such + a + 形容词 + 名词：such a big dog。so 不能直接接 a + 名词；such 后单数可数名词要带 a。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nso + 形容词/副词，such +（a/an）+ 名词；表示「如此……以致……」时后面接 that 从句。\n"
  },
  {
    "id": "reference",
    "title": "Reference（词类大家族总复习）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "英语词分十大词类，句子里必不可少的只有名词和动词；认准词类，句子结构一目了然。",
    "md": "# Reference（词类大家族总复习）\n\n## ① 目标·导入\n\n复习「词类（parts of speech）」这个语法资料库：遇到生句，能快速认出每个词是哪一类。\n\n## ② 规则讲解\n\n英语的词按作用分成十大类：**名词**（人/物的名字）、**动词**（动作或状态）、**形容词**（修饰名词）、**副词**（修饰动词/形容词）、**代词**（代替名词）、**介词**（表示关系）、**连词**（连接词句）、**感叹词**（表达情绪）、**冠词**（a/an/the）等。一个句子必不可少的只有**名词（主语）+ 动词**，其他词类让句子更丰富。\n\n```text\n名词 = 名字    动词 = 动作/状态    形容词 → 修饰名词\n副词 → 修饰动词/形容词    代词 = 代替名词    连词 = 连接\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **The little dog runs quickly.** | 小狗跑得很快。（dog 名词 / runs 动词 / little 形容词 / quickly 副词） |\n| **Wow! She and I like music.** | 哇！她和我喜欢音乐。（Wow 感叹词 / she、I 代词 / and 连词） |\n\n## ④ 易错·对比\n\n**常见错误：只凭「长相」判断词类**\n\n- ❌ 认为 work 永远只是动词。\n- ✅ 看它在句中的作用：I work hard.（动词，工作）/ My work is fun.（名词，工作这件事）\n- 原因：同一个词在不同句子里可能是不同词类，要看位置和作用。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"“The cat sleeps.” 里的 sleeps 是哪类词？\",\n      \"options\": [\n        \"动词\",\n        \"名词\",\n        \"形容词\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"sleeps 表示「睡觉」这个动作，是动词。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"代词（pronoun）的作用是？\",\n      \"options\": [\n        \"代替名词\",\n        \"连接两个句子\",\n        \"表示强烈感情\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"代词用来代替名词，比如 he、she、it、they，避免重复。连接句子是连词，表达感情是感叹词。\"\n    },\n    {\n      \"type\": \"judge\",\n      \"stem\": \"判断对错：“quickly” 是副词，用来修饰动词。\",\n      \"answer\": 0,\n      \"explain\": \"对。quickly 修饰动词，说明动作怎么样，比如 runs quickly（跑得快）。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n英语词分十大词类，句子里必不可少的只有名词和动词；认准词类，句子结构一目了然。\n"
  },
  {
    "id": "enough-and-too",
    "title": "“Enough” and “too”（足够的 enough 与过度的 too）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "enough 表示「足够」：形容词后、名词前；too 表示「太……」：总在形容词/副词前；两者都可接 to do。",
    "md": "# “Enough” and “too”（足够的 enough 与过度的 too）\n\n## ① 目标·导入\n\n学会用 enough 说「刚刚好」，用 too 说「过头了」。\n\n## ② 规则讲解\n\n**enough**（足够）：放在形容词/副词**后面**（old enough、fast enough），放在名词**前面**（enough time）。**too**（太……，过头）：放在形容词/副词**前面**（too hot、too slowly）。两者后面都可以接 **to do**，表示「足够/太过……而（不能）做某事」。\n\n```text\n形容词/副词 + enough (to do)    old enough to go to school\ntoo + 形容词/副词 (to do)       too hot to drink\nenough + 名词                   enough time\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **She is old enough to go to school.** | 她到了上学的年龄（足够大了）。 |\n| **The coffee is too hot to drink.** | 咖啡太烫了，没法喝。 |\n| **We don't have enough time.** | 我们的时间不够。 |\n\n## ④ 易错·对比\n\n**常见错误：enough 的位置放反**\n\n- ❌ He is enough old. / I have money enough.\n- ✅ He is old enough. / I have enough money.\n- 原因：enough 修饰形容词/副词要放后面，修饰名词要放前面。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"He is tall ___ to reach the shelf.\",\n      \"options\": [\n        \"enough\",\n        \"too\",\n        \"very\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「足够高，能够到」用形容词 + enough：tall enough to reach。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"The box is ___ heavy for me. I can't carry it.\",\n      \"options\": [\n        \"too\",\n        \"enough\",\n        \"well\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「太重了，搬不动」用 too + 形容词：too heavy。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「足够的钱」应该怎么说？\",\n      \"options\": [\n        \"enough money\",\n        \"money enough\",\n        \"too money\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"enough 修饰名词时放在名词前面：enough money。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nenough 表示「足够」：形容词后、名词前；too 表示「太……」：总在形容词/副词前；两者都可接 to do。\n"
  },
  {
    "id": "present-continuous-i-am-doing",
    "title": "Present continuous（现在进行时 I am doing）",
    "cefr": "A1",
    "difficulty": 1,
    "summary": "am/is/are + 动词-ing 表示「正在做、还没做完」；be 动词和 -ing 一个都不能少。",
    "md": "# Present continuous（现在进行时 I am doing）\n\n## ① 目标·导入\n\n学会用 am/is/are + doing 说「正在发生的事情」。\n\n## ② 规则讲解\n\n现在进行时 = **am / is / are + 动词-ing**，表示动作已经开始、还没结束，「正在做」。否定加 not（isn't / aren't），疑问把 am/is/are 提前。\n\n```text\nI am doing    He/She/It is doing    We/You/They are doing\n否定：isn't/aren't doing    疑问：Is/Are + 主语 + doing?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **She is reading a book now.** | 她现在正在看书。 |\n| **They aren't playing football.** | 他们没在踢足球。 |\n| **Are you listening to me?** | 你在听我说话吗？ |\n\n## ④ 易错·对比\n\n**常见错误：漏掉 am/is/are**\n\n- ❌ He watching TV.\n- ✅ He is watching TV.\n- 原因：进行时必须有 be 动词和 -ing 两部分，缺一个都不成句子。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我正在写作业。」= I ___ doing my homework.\",\n      \"options\": [\n        \"am\",\n        \"is\",\n        \"are\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"主语是 I，be 动词用 am：I am doing。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Look! The cat ___ sleeping under the tree.\",\n      \"options\": [\n        \"is\",\n        \"are\",\n        \"am\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"The cat 是「它」，单数用 is：The cat is sleeping。\"\n    },\n    {\n      \"type\": \"fill\",\n      \"stem\": \"填上 am / is / are：She ___ singing a song now.\",\n      \"answers\": [\n        \"is\"\n      ],\n      \"explain\": \"主语 She 是第三人称单数，用 is：She is singing。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nam/is/are + 动词-ing 表示「正在做、还没做完」；be 动词和 -ing 一个都不能少。\n"
  },
  {
    "id": "present-simple-i-do",
    "title": "Present simple（一般现在时 I do）",
    "cefr": "A1",
    "difficulty": 1,
    "summary": "一般现在时说习惯和事实；he/she/it 动词加 -s；疑问否定靠 do/does，动词还原。",
    "md": "# Present simple（一般现在时 I do）\n\n## ① 目标·导入\n\n学会用一般现在时说「总是这样」的习惯和事实。\n\n## ② 规则讲解\n\n一般现在时表示**经常性、反复发生**的事或**普遍事实**。he/she/it 作主语时动词加 **-s/-es**（works、goes）。疑问和否定请 do/does 帮忙，后面动词**还原**。\n\n```text\nI/You/We/They work.    He/She/It works.\n否定：don't/doesn't + 动词原形    疑问：Do/Does + 主语 + 动词原形?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I get up at seven every day.** | 我每天七点起床。 |\n| **The sun rises in the east.** | 太阳从东方升起。 |\n| **She doesn't like milk.** | 她不喜欢牛奶。 |\n\n## ④ 易错·对比\n\n**常见错误：does 后面动词还带 -s**\n\n- ❌ She doesn't likes milk.\n- ✅ She doesn't like milk.\n- 原因：-s 已经体现在 does 里了，后面的动词要用原形。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"He ___ football every Sunday.\",\n      \"options\": [\n        \"plays\",\n        \"play\",\n        \"playing\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"He 是第三人称单数，一般现在时动词加 -s：plays。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我不喝茶。」= I ___ drink tea.\",\n      \"options\": [\n        \"don't\",\n        \"doesn't\",\n        \"am not\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"主语 I 的否定用 don't + 动词原形：don't drink。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"Does she like apples?\",\n        \"Does she likes apples?\",\n        \"Do she like apples?\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"Does 提问后动词还原 like；she 配 Does，不配 Do。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n一般现在时说习惯和事实；he/she/it 动词加 -s；疑问否定靠 do/does，动词还原。\n"
  },
  {
    "id": "present-continuous-and-present-simple-1-i-am-doing-and-i-do",
    "title": "Present continuous and present simple 1（I am doing 与 I do 对比）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "I am doing 说此刻或近期正在发生；I do 说一贯习惯或长期事实；I'm always doing 常带抱怨语气。",
    "md": "# Present continuous and present simple 1（I am doing 与 I do 对比）\n\n## ① 目标·导入\n\n分清现在进行时（正在发生）和一般现在时（总是发生）。\n\n## ② 规则讲解\n\n**进行时**：说话时或最近正在发生、还没结束的事（Listen! She is singing.）；**临时**情况也用进行时（I'm living with friends this month.）。**一般现在时**：一贯的习惯、普遍事实（Water boils at 100°C.）；**长期**情况用一般现在时（My parents live in London.）。特别注意：`I'm always doing` 表示「老是……」，常带抱怨语气。\n\n```text\n正在进行/临时 → I am doing\n一贯习惯/长期事实 → I do\n抱怨「老是…」→ I'm always doing\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I'm reading a great book these days.** | 这几天我在读一本好书。 |\n| **I read every night before bed.** | 我每晚睡前都读书。 |\n| **She's always losing her keys!** | 她老是丢钥匙！（抱怨） |\n\n## ④ 易错·对比\n\n**常见错误：习惯性动作用进行时**\n\n- ❌ I am going to school every day.\n- ✅ I go to school every day.\n- 原因：every day 表示每天的习惯，用一般现在时，不用 -ing。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Listen! Someone ___ the piano.\",\n      \"options\": [\n        \"is playing\",\n        \"plays\",\n        \"play\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"Listen! 提示此刻正在发生，用现在进行时 is playing。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Water ___ at 100 degrees.（科学事实）\",\n      \"options\": [\n        \"boils\",\n        \"is boiling\",\n        \"boil\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"普遍事实用一般现在时；Water 是单数，动词加 -s：boils。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「你老是看手机！（有点抱怨）」= You're always ___ at your phone.\",\n      \"options\": [\n        \"looking\",\n        \"look\",\n        \"looks\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"be always doing 表示「老是做某事」，常带抱怨语气。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nI am doing 说此刻或近期正在发生；I do 说一贯习惯或长期事实；I'm always doing 常带抱怨语气。\n"
  },
  {
    "id": "past-simple-i-did",
    "title": "Past simple（一般过去时 I did）",
    "cefr": "A1",
    "difficulty": 1,
    "summary": "规则动词加 -ed，不规则动词要记（go→went、see→saw）；疑问否定用 did/didn't，动词还原。",
    "md": "# Past simple（一般过去时 I did）\n\n## ① 目标·导入\n\n学会用一般过去时说「过去发生、已经结束」的事。\n\n## ② 规则讲解\n\n一般过去时表示过去发生并结束的事。规则动词加 **-ed**（worked、played），不规则动词要记（go→went、see→saw、write→wrote）。否定用 **didn't + 动词原形**，疑问用 **Did + 主语 + 动词原形**。be 的过去式是 was/were。\n\n```text\n肯定：动词-ed / 不规则过去式\n否定：didn't + 动词原形    疑问：Did + 主语 + 动词原形?\nbe → was / were\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **We watched a film yesterday.** | 我们昨天看了一场电影。 |\n| **She didn't go to school.** | 她没去上学。 |\n| **Did you enjoy the party?** | 聚会你玩得开心吗？ |\n\n## ④ 易错·对比\n\n**常见错误：did/didn't 后动词用过去式**\n\n- ❌ I didn't went home.\n- ✅ I didn't go home.\n- 原因：didn't 已经表示「过去 + 否定」，动词用原形。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"go 的过去式是：\",\n      \"options\": [\n        \"went\",\n        \"goed\",\n        \"going\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"go 是不规则动词：go → went。不能加 -ed。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我昨天没踢足球。」= I ___ play football yesterday.\",\n      \"options\": [\n        \"didn't\",\n        \"don't\",\n        \"wasn't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"昨天是过去，否定用 didn't + 动词原形 play。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"___ you see Tom last night?\",\n      \"options\": [\n        \"Did\",\n        \"Do\",\n        \"Was\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"昨晚是过去时间，疑问用 Did + 主语 + 动词原形 see。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n规则动词加 -ed，不规则动词要记（go→went、see→saw）；疑问否定用 did/didn't，动词还原。\n"
  },
  {
    "id": "past-continuous-i-was-doing",
    "title": "Past continuous（过去进行时 I was doing）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "was/were + doing 表示过去某时刻「正在做」；长背景用过去进行，短动作用一般过去，when/while 连接。",
    "md": "# Past continuous（过去进行时 I was doing）\n\n## ① 目标·导入\n\n学会用 was/were + doing 描述「过去某个时刻正在做什么」。\n\n## ② 规则讲解\n\n过去进行时 = **was/were + 动词-ing**，表示过去某时刻动作正在进行、还没结束。常和一般过去时搭配：**长的背景动作用进行时，短的打断动作用过去式**，用 when/while 连接。\n\n```text\nI/He/She/It was doing    We/You/They were doing\n长背景 + when + 短动作：I was sleeping when the phone rang.\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I was sleeping at ten last night.** | 昨晚十点我正在睡觉。 |\n| **It was raining when we left.** | 我们出门时正下着雨。 |\n| **While I was cooking, the phone rang.** | 我在做饭时，电话响了。 |\n\n## ④ 易错·对比\n\n**常见错误：状态动词用进行时**\n\n- ❌ We were knowing each other well.\n- ✅ We knew each other well.\n- 原因：know、want、like 等状态动词一般不用 -ing 形式。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"At eight yesterday evening, she ___ TV.\",\n      \"options\": [\n        \"was watching\",\n        \"watched\",\n        \"watches\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「昨晚八点那一刻正在看」是过去某时刻的进行，用 was watching。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「当我在做作业时，妈妈回来了。」= ___ I was doing my homework, Mum came home.\",\n      \"options\": [\n        \"While\",\n        \"Because\",\n        \"So\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"while 表示「在……期间」，连接同时进行的背景动作。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"I wanted to go home.\",\n        \"I was wanting to go home.\",\n        \"I am wanting to go home.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"want 是状态动词，一般不用进行时。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nwas/were + doing 表示过去某时刻「正在做」；长背景用过去进行，短动作用一般过去，when/while 连接。\n"
  },
  {
    "id": "present-perfect-1-i-have-done",
    "title": "Present perfect 1（现在完成时 I have done）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "have/has + 过去分词，说过去发生但对现在有影响的事；常配 just、already、yet；有具体过去时间就改用一般过去时。",
    "md": "# Present perfect 1（现在完成时 I have done）\n\n## ① 目标·导入\n\n学会用 have/has + 过去分词说「发生过、现在仍有影响」的事。\n\n## ② 规则讲解\n\n现在完成时 = **have/has + 过去分词**（done、lost、written…），表示过去的动作对**现在**有影响或结果（He has lost his key = 钥匙现在还没找到）。常和 **just**（刚）、**already**（已经）、**yet**（疑问否定句末尾）连用。\n\n```text\nI/You/We/They have done    He/She/It has done\nI've just finished. / I've already eaten. / Have you finished yet?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I've lost my key.** | 我把钥匙弄丢了。（现在还没有） |\n| **She has just finished her homework.** | 她刚做完作业。 |\n| **Have you seen my bag yet?** | 你见到我的包了吗？ |\n\n## ④ 易错·对比\n\n**常见错误：和具体过去时间连用**\n\n- ❌ I have seen him yesterday.\n- ✅ I saw him yesterday.\n- 原因：yesterday 这类明确的过去时间要用一般过去时，不用现在完成时。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我已经吃过早饭了。」= I ___ already had breakfast.\",\n      \"options\": [\n        \"have\",\n        \"has\",\n        \"had\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"主语 I 配 have：I have already had breakfast。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"I saw him yesterday.\",\n        \"I have seen him yesterday.\",\n        \"I have see him yesterday.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"有 yesterday 这样具体的过去时间，用一般过去时 saw。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Have you ___ your homework yet?\",\n      \"options\": [\n        \"finished\",\n        \"finish\",\n        \"finishing\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"have + 过去分词构成现在完成时：Have you finished…?\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhave/has + 过去分词，说过去发生但对现在有影响的事；常配 just、already、yet；有具体过去时间就改用一般过去时。\n"
  },
  {
    "id": "present-perfect-continuous-i-have-been-doing",
    "title": "Present perfect continuous（现在完成进行时 I have been doing）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "have/has been doing 强调动作从过去持续到现在（可能刚停）；know、like 等状态动词用 have done。",
    "md": "# Present perfect continuous（现在完成进行时 I have been doing）\n\n## ① 目标·导入\n\n学会用 have/has been doing 说「一直在做、持续到现在」。\n\n## ② 规则讲解\n\n现在完成进行时 = **have/has been + 动词-ing**：①动作从过去开始**持续到现在**，常配 for/since/how long；②动作**刚刚停止**，但留下了看得见的结果（你气喘吁吁——刚才一直在跑？）。\n\n```text\nhave/has been + doing\nIt has been raining for two hours.（还在下）\nYou look tired. Have you been running?（刚停）\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **It has been raining for two hours.** | 雨已经下了两个小时了。（还在下） |\n| **You look tired. Have you been running?** | 你看起来很累，刚跑步了吗？ |\n| **I've been learning English since January.** | 我从一月起一直在学英语。 |\n\n## ④ 易错·对比\n\n**常见错误：状态动词用完成进行时**\n\n- ❌ I've been knowing him for years.\n- ✅ I've known him for years.\n- 原因：know、like、have（拥有）等状态动词一般不用 -ing 形式。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"She's still on the phone. She ___ for an hour.\",\n      \"options\": [\n        \"has been talking\",\n        \"talks\",\n        \"talked\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「一直在打、还没停」强调持续过程，用 has been talking。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"I've known him for years.\",\n        \"I've been knowing him for years.\",\n        \"I am knowing him.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"know 是状态动词，不用进行时，用现在完成时 have known。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"The ground is wet. It ___ raining.\",\n      \"options\": [\n        \"has been\",\n        \"is\",\n        \"will be\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"地湿是刚停的雨留下的痕迹，用现在完成进行时 has been raining。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhave/has been doing 强调动作从过去持续到现在（可能刚停）；know、like 等状态动词用 have done。\n"
  },
  {
    "id": "present-perfect-continuous-and-simple-i-have-been-doing-and-i-have-done",
    "title": "Present perfect continuous and simple（I have been doing 与 I have done 对比）",
    "cefr": "B1",
    "difficulty": 3,
    "summary": "have been doing 重在过程、持续多久；have done 重在结果、完成多少；问数量用完成时。",
    "md": "# Present perfect continuous and simple（I have been doing 与 I have done 对比）\n\n## ① 目标·导入\n\n分清现在完成进行时（重过程）和现在完成时（重结果）。\n\n## ② 规则讲解\n\n**进行时**重在「动作本身、过程、持续了多久」，做没做完不重要（I've been reading all morning.）。**完成时**重在「结果、已完成」，常说**做了多少、多少次**（I've read three books.）。问 how long 多用进行时；问 how many / how much 必须用完成时。\n\n```text\n过程/持续多久 → have been doing\n结果/完成多少 → have done\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I've been reading all morning.** | 我一上午都在看书。（可能还没看完） |\n| **I've read three books this month.** | 这个月我读完了三本书。 |\n| **She's painted her bedroom. It looks great.** | 她把卧室刷好了，焕然一新。（强调结果） |\n\n## ④ 易错·对比\n\n**常见错误：表示数量用进行时**\n\n- ❌ I've been reading three books this month.\n- ✅ I've read three books this month.\n- 原因：提到「多少本、多少次」是完成的结果，用 have done。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I ___ five emails this morning.（已写完五封）\",\n      \"options\": [\n        \"have written\",\n        \"have been writing\",\n        \"am writing\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"强调完成数量（five emails），用现在完成时 have written。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"How long ___ for me?\",\n      \"options\": [\n        \"have you been waiting\",\n        \"are you waiting\",\n        \"do you wait\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"问「等了多久」，强调持续过程，用现在完成进行时。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"想说「墙刷好了，很漂亮」，强调结果，该用：\",\n      \"options\": [\n        \"She has painted the wall.\",\n        \"She has been painting the wall.\",\n        \"She paints the wall.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"强调完成的结果用 has painted；has been painting 只说过程，不管完没完。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhave been doing 重在过程、持续多久；have done 重在结果、完成多少；问数量用完成时。\n"
  },
  {
    "id": "how-long-have-you-been",
    "title": "How long have you (been)…?（持续了多久）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "问「从过去持续到现在多久」用 How long + 现在完成时，答用 for/since；know 等状态动词用 have known。",
    "md": "# How long have you (been)…?（持续了多久）\n\n## ① 目标·导入\n\n学会用 How long have you (been)…? 问「持续了多久」。\n\n## ② 规则讲解\n\n问一件从过去开始、**持续到现在**的事有多久，用 **How long + have/has + 主语 (+ been doing / 过去分词)**，回答用 for/since。注意要用现在完成时，不能用一般现在时。know、have 等状态动词用 **have known / have had**（不用 been knowing）。\n\n```text\nHow long have you been working here?\nHow long have you known Jane?\n回答：For ten years. / Since 2015.\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **How long have you lived here?** | 你在这儿住多久了？ |\n| **How long has she been waiting?** | 她等了多久了？ |\n| **How long have you known Jane?** | 你认识简多久了？ |\n\n## ④ 易错·对比\n\n**常见错误：用一般现在时问持续时间**\n\n- ❌ How long are you married?\n- ✅ How long have you been married?\n- 原因：「结婚多久了」从过去持续到现在，要用现在完成时。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"___ have you been learning English?\",\n      \"options\": [\n        \"How long\",\n        \"How often\",\n        \"How many\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"问持续的时间长度用 How long。How often 问频率，How many 问数量。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"How long ___ each other?\",\n      \"options\": [\n        \"have you known\",\n        \"do you know\",\n        \"are you knowing\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"认识从过去持续到现在，用现在完成时；know 是状态动词，用 have known。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"How long has he worked here?\",\n        \"How long is he working here?\",\n        \"How long does he work here?\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「在这儿工作多久了」持续到现在，用现在完成时 has worked。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n问「从过去持续到现在多久」用 How long + 现在完成时，答用 for/since；know 等状态动词用 have known。\n"
  },
  {
    "id": "for-and-since-when-and-how-long",
    "title": "For and since（for 与 since；When 与 How long）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "for + 时间段，since + 起点；When + 过去式问时间点，How long + 现在完成时问持续多久。",
    "md": "# For and since（for 与 since；When 与 How long）\n\n## ① 目标·导入\n\n分清 for 与 since，以及 When…? 与 How long…? 的用法。\n\n## ② 规则讲解\n\n**for + 一段时间**（for two hours、for ten years）；**since + 起点**（since Monday、since 2020）。问「什么时候开始」用 **When + 一般过去时**；问「持续多久」用 **How long + 现在完成时**。\n\n```text\nfor + 时间段：for five years\nsince + 起点：since 2020 / since we met\nWhen did it start? ↔ How long has it been going on?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **We've lived here for five years.** | 我们在这儿住了五年了。 |\n| **I've had this bike since 2022.** | 这辆自行车是 2022 年买的，一直骑到现在。 |\n| **When did it start raining? — It's been raining for an hour.** | 雨什么时候开始下的？——已经下一个小时了。 |\n\n## ④ 易错·对比\n\n**常见错误：时间段前用 since**\n\n- ❌ I've been here since three days.\n- ✅ I've been here for three days.\n- 原因：three days 是一段时长，用 for；since 后面要跟起点（since Monday）。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"She has been here ___ Monday.\",\n      \"options\": [\n        \"since\",\n        \"for\",\n        \"at\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"Monday 是时间起点，用 since。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I've known him ___ ten years.\",\n      \"options\": [\n        \"for\",\n        \"since\",\n        \"from\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"ten years 是一段时间，用 for。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"想问「雨是什么时候开始下的？」应该问：\",\n      \"options\": [\n        \"When did it start raining?\",\n        \"How long did it start raining?\",\n        \"When has it started raining?\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"问开始的时间点用 When + 一般过去时。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nfor + 时间段，since + 起点；When + 过去式问时间点，How long + 现在完成时问持续多久。\n"
  },
  {
    "id": "present-perfect-and-past-1-i-have-done-and-i-did",
    "title": "Present perfect and past 1（I have done 与 I did 对比）",
    "cefr": "B1",
    "difficulty": 3,
    "summary": "have done 是「和现在有关的新闻」；did 只说过去的事；讲完新闻后补充细节改用一般过去时。",
    "md": "# Present perfect and past 1（I have done 与 I did 对比）\n\n## ① 目标·导入\n\n分清现在完成时（与现在有关）和一般过去时（只谈过去）。\n\n## ② 规则讲解\n\n**现在完成时**是「现在时」：报道新闻、说明现在的情况（He has lost his key = 现在还没找到）。**一般过去时**只说过去发生了什么，不管现在（He lost his key = 不知道现在找没找到）。先用完成时报新闻，接着讲细节时改用过去时；**很久以前、已故人物**的事只用过去时（Mozart wrote…）。\n\n```text\n新闻/影响现在 → have done\n只谈过去/细节 → did\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I've repaired the bike. It works now.** | 我把自行车修好了，现在能骑了。 |\n| **Who invented the telephone?** | 谁发明了电话？（过去的事） |\n| **Ow! I've burnt myself. — How did you do that?** | 哎哟！我烫着自己了。——怎么弄的？（新闻用完成时，细节用过去时） |\n\n## ④ 易错·对比\n\n**常见错误：久远过去用现在完成时**\n\n- ❌ Mozart has written more than 600 pieces of music.\n- ✅ Mozart wrote more than 600 pieces of music.\n- 原因：莫扎特是过去的人物，写曲是纯过去的事，用一般过去时。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Tom can't find his key. He ___ it.\",\n      \"options\": [\n        \"has lost\",\n        \"lost\",\n        \"loses\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"钥匙现在还没找到，对现在有影响，用 has lost。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「谁发明了电话？」= Who ___ the telephone?\",\n      \"options\": [\n        \"invented\",\n        \"has invented\",\n        \"invents\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"发明电话是久远过去的事，用一般过去时 invented。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"Mozart wrote more than 600 pieces of music.\",\n        \"Mozart has written more than 600 pieces of music.\",\n        \"Mozart is writing more than 600 pieces of music.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"莫扎特是已故人物，他写曲属于纯过去，用 wrote。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhave done 是「和现在有关的新闻」；did 只说过去的事；讲完新闻后补充细节改用一般过去时。\n"
  },
  {
    "id": "past-perfect-i-had-done",
    "title": "Past perfect（过去完成时 I had done）",
    "cefr": "B1",
    "difficulty": 3,
    "summary": "had + 过去分词表示「过去的过去」：比另一个过去动作更早完成。",
    "md": "# Past perfect（过去完成时 I had done）\n\n## ① 目标·导入\n\n学会用 had done 表示「过去的过去」。\n\n## ② 规则讲解\n\n过去完成时 = **had + 过去分词**，表示在**过去某时之前**已经完成的动作，即「过去的过去」。常和 when / already / never / because 搭配，先有一个过去时间点，再往前回看。\n\n```text\nhad + 过去分词\nWhen Sarah arrived, Paul had already gone home.\n（arrive 是过去，gone home 比它更早）\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **When Sarah arrived, Paul had already gone home.** | 萨拉到达时，保罗已经回家了。 |\n| **I couldn't buy tickets because I had lost my wallet.** | 我买不了票，因为（之前）钱包丢了。 |\n| **They hadn't flown before.** | 他们以前从没坐过飞机。 |\n\n## ④ 易错·对比\n\n**常见错误：普通的过去也用过去完成时**\n\n- ❌ I had got up at seven yesterday.（无对照）\n- ✅ I got up at seven yesterday.\n- 原因：过去完成时要和「更晚的过去」对比才用；单独说一件过去的事用一般过去时。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"When I got to the station, the train ___ already ___.\",\n      \"options\": [\n        \"had … left\",\n        \"has … left\",\n        \"is … leaving\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"到站是过去，火车离开比到站更早，是「过去的过去」，用 had left。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"She was hungry because she ___ lunch.\",\n      \"options\": [\n        \"hadn't had\",\n        \"doesn't have\",\n        \"hasn't had\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"was hungry 是过去，没吃饭比它更早，用 hadn't had。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"过去完成时表示：\",\n      \"options\": [\n        \"过去的过去\",\n        \"现在的状态\",\n        \"将来的动作\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"had done 表示比过去某时更早发生或完成的动作。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhad + 过去分词表示「过去的过去」：比另一个过去动作更早完成。\n"
  },
  {
    "id": "past-perfect-continuous-i-had-been-doing",
    "title": "Past perfect continuous（过去完成进行时 I had been doing）",
    "cefr": "B2",
    "difficulty": 3,
    "summary": "had been doing 表示「直到过去某时一直在做」，强调过程和原因；状态动词用 had done。",
    "md": "# Past perfect continuous（过去完成进行时 I had been doing）\n\n## ① 目标·导入\n\n学会用 had been doing 说「（那时之前）一直在做」。\n\n## ② 规则讲解\n\n过去完成进行时 = **had been + 动词-ing**，表示在过去某时之前**一直在进行**的动作，常用来解释当时的状态或原因（他累是因为忙了一天）。对比：had been doing 重在过程/原因，had done 重在完成。\n\n```text\nhad been + doing\nThe ground was wet. It had been raining.\nWe'd been playing for half an hour when it started to rain.\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **The ground was wet. It had been raining.** | 地是湿的。（因为）之前一直在下雨。 |\n| **Tom was tired because he'd been working all day.** | 汤姆很累，因为他忙了一整天。 |\n| **We'd been playing tennis for half an hour when it started to rain.** | 我们打了半小时网球，突然下起雨来。 |\n\n## ④ 易错·对比\n\n**常见错误：状态动词用过去完成进行时**\n\n- ❌ I'd been knowing him for years.\n- ✅ I'd known him for years.\n- 原因：know、like 等状态动词不用 -ing 形式。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Her eyes were red. She ___ crying.\",\n      \"options\": [\n        \"had been\",\n        \"is\",\n        \"will be\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"讲过去的事，眼睛红是因为此前一直在哭，用 had been crying。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"They ___ for two hours when the bus finally came.\",\n      \"options\": [\n        \"had been waiting\",\n        \"have been waiting\",\n        \"are waiting\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"车来是过去，等待在车来之前持续了两个小时，用过去完成进行时。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"过去完成进行时强调：\",\n      \"options\": [\n        \"过去某时之前一直在进行\",\n        \"现在正在做\",\n        \"将来会完成\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"had been doing 表示在过去某时刻之前持续进行的动作，常解释原因。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhad been doing 表示「直到过去某时一直在做」，强调过程和原因；状态动词用 had done。\n"
  },
  {
    "id": "have-and-have-got",
    "title": "Have and have got（have 与 have got）",
    "cefr": "A2",
    "difficulty": 1,
    "summary": "表示「拥有」时 have 和 have got 意思相同；过去式用 had 不带 got；have breakfast 等短语不能用 got。",
    "md": "# Have and have got（have 与 have got）\n\n## ① 目标·导入\n\n弄清 have 和 have got 什么时候一样、什么时候不一样。\n\n## ② 规则讲解\n\n表示**拥有、关系、疾病**等时，have 和 have got 意思相同，可互换：I have a car. = I've got a car.。过去式用 **had**（一般不带 got）。但 **have breakfast / have a shower / have a good time** 等「做某事」的短语不能用 got。\n\n```text\n拥有：have = have got → I have / I've got a sister.\n过去：had（不带 got）\n吃饭/洗澡等：只能用 have\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **She has (got) two brothers.** | 她有两个兄弟。 |\n| **I've got a headache.** | 我头疼。 |\n| **Did you have a good time?** | 你玩得开心吗？（不能说 got） |\n\n## ④ 易错·对比\n\n**常见错误：吃饭也用 have got**\n\n- ❌ I've got breakfast at seven every day.\n- ✅ I have breakfast at seven every day.\n- 原因：have breakfast 的 have 表示「吃」，不是「拥有」，不能用 got。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我有一辆新自行车。」= I ___ got a new bike.\",\n      \"options\": [\n        \"have\",\n        \"had\",\n        \"do\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"have got = have，表示拥有：I've got a new bike。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"I have breakfast at seven.\",\n        \"I've got breakfast at seven.\",\n        \"I have got breakfast at seven.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"have breakfast 表示「吃早饭」，不能用 got。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"“have a cold（感冒）”的过去式该写：\",\n      \"options\": [\n        \"had a cold\",\n        \"had got a cold\",\n        \"has a cold\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"过去的「拥有/患病」用 had，一般不带 got。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n表示「拥有」时 have 和 have got 意思相同；过去式用 had 不带 got；have breakfast 等短语不能用 got。\n"
  },
  {
    "id": "used-to-do",
    "title": "Used to（过去常常 used to do）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "used to + 动词原形表示「过去常常、现在不再」；没有现在式，疑问用 Did you use to…?",
    "md": "# Used to（过去常常 used to do）\n\n## ① 目标·导入\n\n学会用 used to do 说「过去常常……（现在不了）」。\n\n## ② 规则讲解\n\n**used to + 动词原形**表示过去经常发生的习惯或状态，**现在已经不是这样了**。疑问式：**Did you use to…?** 否定式：didn't use to。注意：used to 只用于过去，没有现在式。\n\n```text\nused to + 动词原形：I used to play tennis.（现在不打了）\n疑问：Did you use to …?    否定：didn't use to …\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I used to play tennis a lot.** | 我过去常打网球。（现在不常打了） |\n| **This building used to be a cinema.** | 这栋楼以前是电影院。 |\n| **Did you use to eat lots of sweets?** | 你小时候常吃很多糖吗？ |\n\n## ④ 易错·对比\n\n**常见错误：用 use to 说现在的习惯**\n\n- ❌ I use to swim every day.（想说现在的习惯）\n- ✅ I swim every day.\n- 原因：used to 只表示过去；现在的习惯用一般现在时。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"She ___ live in Beijing, but now she lives in Shanghai.\",\n      \"options\": [\n        \"used to\",\n        \"uses to\",\n        \"is use to\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「过去住北京、现在不了」用 used to live。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"Did you use to play football?\",\n        \"Did you used to play football?\",\n        \"Do you use to play football?\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"疑问式用 Did + use to（动词还原）：Did you use to…?\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"There ___ a park here, but now there is a mall.\",\n      \"options\": [\n        \"used to be\",\n        \"used to is\",\n        \"use to being\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「这里以前有个公园」用 there used to be。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nused to + 动词原形表示「过去常常、现在不再」；没有现在式，疑问用 Did you use to…?\n"
  },
  {
    "id": "present-tenses-i-am-doing-i-do-for-the-future",
    "title": "Present tenses for the future（用现在时谈将来）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "安排好的事用现在进行时（I'm seeing…），时刻表日程用一般现在时（The train leaves…）。",
    "md": "# Present tenses for the future（用现在时谈将来）\n\n## ① 目标·导入\n\n学会用现在进行时和一般现在时谈论将来的安排。\n\n## ② 规则讲解\n\n**已经安排好的事**用现在进行时：I'm meeting Kate tomorrow.。**时刻表、日程**（火车、电影、课表）用一般现在时：The train leaves at 11.30.。已经安排好的事一般不用 will。\n\n```text\n个人安排（已定）→ be doing：I'm going to the dentist tomorrow.\n时刻表/日程 → 一般现在时：The film starts at eight.\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **What are you doing tonight? — I'm going to the cinema.** | 你今晚干什么？——我去看电影。 |\n| **My train leaves at 11.30.** | 我的火车十一点半开。 |\n| **The film starts at eight o'clock.** | 电影八点开始。 |\n\n## ④ 易错·对比\n\n**常见错误：已安排的事用 will 提问**\n\n- ❌ What will you do tonight?（问已有安排）\n- ✅ What are you doing tonight?\n- 原因：问已经定好的安排，用现在进行时。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I ___ the dentist tomorrow morning.（已约好）\",\n      \"options\": [\n        \"am seeing\",\n        \"see\",\n        \"saw\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"已经约好的安排用现在进行时：am seeing。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"The train ___ at nine every morning.\",\n      \"options\": [\n        \"leaves\",\n        \"is leaving\",\n        \"left\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"时刻表用一般现在时：leaves。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「电影几点开始？」（按排片表）= What time ___ the film start?\",\n      \"options\": [\n        \"does\",\n        \"is\",\n        \"was\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"按时刻表提问用一般现在时：does the film start。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n安排好的事用现在进行时（I'm seeing…），时刻表日程用一般现在时（The train leaves…）。\n"
  },
  {
    "id": "im-going-to-do",
    "title": "I'm going to（打算做 be going to）",
    "cefr": "A2",
    "difficulty": 1,
    "summary": "be going to + 动词原形：表示打算做的事，或根据眼前迹象预测将要发生的事。",
    "md": "# I'm going to（打算做 be going to）\n\n## ① 目标·导入\n\n学会用 be going to do 说「打算做」和「眼看就要发生」。\n\n## ② 规则讲解\n\n**be going to + 动词原形**：①表示**已经决定、打算**做的事（I'm going to clean my room.）；②根据**眼前的迹象**预测将要发生的事（看乌云——要下雨了）。\n\n```text\nam/is/are + going to + 动词原形\nI'm going to learn to cook.\nLook at the clouds! It's going to rain.\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I'm going to clean my room this weekend.** | 我打算这周末打扫房间。 |\n| **Look at those black clouds! It's going to rain.** | 看那些乌云！要下雨了。 |\n| **She's going to buy a new car.** | 她打算买一辆新车。 |\n\n## ④ 易错·对比\n\n**常见错误：漏掉 be 动词**\n\n- ❌ I going to study.\n- ✅ I am going to study.\n- 原因：be going to 里的 am/is/are 不能少。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"We ___ going to have a picnic tomorrow.\",\n      \"options\": [\n        \"are\",\n        \"is\",\n        \"be\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"主语 We 配 are：We are going to…\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"天乌云密布，你可以说：It's going to ___.\",\n      \"options\": [\n        \"rain\",\n        \"raining\",\n        \"rained\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"going to 后接动词原形：going to rain。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我打算学做饭。」= I'm going ___ learn to cook.\",\n      \"options\": [\n        \"to\",\n        \"for\",\n        \"at\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"固定结构 be going to + 动词原形。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nbe going to + 动词原形：表示打算做的事，或根据眼前迹象预测将要发生的事。\n"
  },
  {
    "id": "will-and-shall-1",
    "title": "Will and shall 1（will 与 shall 初探）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "will 用于当场决定、承诺、主动帮忙；Shall I/we…? 征求意见；已安排的事不用 will。",
    "md": "# Will and shall 1（will 与 shall 初探）\n\n## ① 目标·导入\n\n学会用 will/'ll 表示当场决定、承诺和主动帮忙。\n\n## ② 规则讲解\n\n**will**：①说话**当场决定**（电话响了——I'll answer it.）；②**承诺、主动帮忙、答应**（I'll help you. / I won't be late.）。won't 还可表示「拒绝、不肯」。注意：**已经安排好**的事不用 will（用 be doing）。征求意见、建议用 **Shall I/we…?**\n\n```text\n当场决定/承诺/帮忙 → will ('ll)，否定 won't\n征求意见 → Shall I …? / Shall we …?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **The phone is ringing. I'll answer it.** | 电话响了，我去接。 |\n| **I promise I won't be late.** | 我保证不迟到。 |\n| **Shall I open the window?** | 要我把窗户打开吗？ |\n\n## ④ 易错·对比\n\n**常见错误：已安排的事用 will**\n\n- ❌ I'll go to the cinema tonight.（早已约好）\n- ✅ I'm going to the cinema tonight.\n- 原因：事先安排好的事用现在进行时，不用 will。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"“It's cold in here.” “OK, I ___ close the window.”（当场决定）\",\n      \"options\": [\n        \"will\",\n        \"do\",\n        \"did\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"说话时刚做的决定用 will：I'll close the window。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"想征求对方意见「我开窗好吗？」：___ I open the window?\",\n      \"options\": [\n        \"Shall\",\n        \"Did\",\n        \"Am\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"Shall I…? 用来征求意见、主动提议。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"I promise I won't be late.\",\n        \"I promise I don't be late.\",\n        \"I promise I'm not be late.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"承诺用 will：I won't (= will not) be late。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nwill 用于当场决定、承诺、主动帮忙；Shall I/we…? 征求意见；已安排的事不用 will。\n"
  },
  {
    "id": "i-will-and-im-going-to",
    "title": "I will and I'm going to（will 与 going to 对比）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "当场决定用 will，事先打算用 going to；预测时眼前有迹象用 going to，凭判断用 will。",
    "md": "# I will and I'm going to（will 与 going to 对比）\n\n## ① 目标·导入\n\n分清 will（刚决定）和 be going to（早打算）。\n\n## ② 规则讲解\n\n宣布**当场做出的决定**用 **will**；说**事先已决定**的计划用 **be going to**。预测未来：眼前有**迹象**用 going to（乌云→要下雨）；凭经验**判断**多用 will。\n\n```text\n当场决定 → will\n事先打算 → be going to\n有迹象的预测 → be going to\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **'We need milk.' 'Really? I'll go and buy some.'** | 「没牛奶了。」「真的？那我去买。」（刚决定，用 will） |\n| **I'm going to visit my grandma this weekend. I've decided.** | 这周末我去看奶奶，我已经决定了。（用 going to） |\n| **Look out! You're going to fall!** | 小心！你要摔倒了！（有迹象） |\n\n## ④ 易错·对比\n\n**常见错误：刚听到消息就用 going to**\n\n- ❌ 'Anna is in hospital.' 'Really? I'm going to visit her.'（刚听说，当场决定）\n- ✅ 'Really? I'll visit her.'\n- 原因：当场做出的决定用 will；早就计划好的才用 going to。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"'The doorbell is ringing.' 'OK, I ___ get it.'\",\n      \"options\": [\n        \"will\",\n        \"am going to\",\n        \"going to\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"听到门铃当场决定去开门，用 will。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"We ___ going to have a party on Saturday. We've planned it.\",\n      \"options\": [\n        \"are\",\n        \"is\",\n        \"will\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"早就计划好的事用 be going to；We 配 are。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Look at those black clouds! It ___ rain.\",\n      \"options\": [\n        \"is going to\",\n        \"shall\",\n        \"is\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"眼前有乌云作迹象，预测用 is going to。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n当场决定用 will，事先打算用 going to；预测时眼前有迹象用 going to，凭判断用 will。\n"
  },
  {
    "id": "will-be-doing-and-will-have-done",
    "title": "Will be doing and will have done（将来进行时与将来完成时）",
    "cefr": "B2",
    "difficulty": 3,
    "summary": "will be doing：将来某时正在做；will have done：到将来某时将已完成，常配 by / by the time。",
    "md": "# Will be doing and will have done（将来进行时与将来完成时）\n\n## ① 目标·导入\n\n学会将来进行时和将来完成时。\n\n## ② 规则讲解\n\n**will be doing**（将来进行时）：将来某时刻**正在做**某事（明天这个时候，我正在沙滩上躺着呢）。**will have done**（将来完成时）：**到将来某时之前已经完成**，常配 by tomorrow / by the time…。\n\n```text\nwill be doing → 将来某时正在进行\nwill have done → 到将来某时已完成（by + 时间）\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **This time tomorrow, I'll be lying on the beach.** | 明天这个时候，我正躺在沙滩上呢。 |\n| **Don't phone at seven. We'll be eating.** | 七点别打电话，我们那时正在吃饭。 |\n| **The film will have started by the time we get there.** | 等我们到那儿，电影已经开映了。 |\n\n## ④ 易错·对比\n\n**常见错误：将来完成时没有截止时间**\n\n- ❌ I will have finished my homework.（没有时间参照，突兀）\n- ✅ I will have finished my homework by nine.\n- 原因：将来完成时要有一个将来的截止时间（by…）作参照。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"At ten tomorrow morning, she ___ in her office.\",\n      \"options\": [\n        \"will be working\",\n        \"works\",\n        \"worked\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"将来某时刻正在进行，用将来进行时 will be working。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"By next year, they ___ here for ten years.\",\n      \"options\": [\n        \"will have lived\",\n        \"live\",\n        \"are living\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「到明年就满十年」是将来到某时完成，用 will have lived。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"将来完成时的结构是：\",\n      \"options\": [\n        \"will have + 过去分词\",\n        \"will be + 动词-ing\",\n        \"will + 动词原形\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"will have done：到将来某时将已完成。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nwill be doing：将来某时正在做；will have done：到将来某时将已完成，常配 by / by the time。\n"
  },
  {
    "id": "when-i-do-and-when-ive-done-if-and-when",
    "title": "When I do and when I've done（when/if 从句用现在时）",
    "cefr": "B1",
    "difficulty": 3,
    "summary": "表示将来时，when/if 等从句里用现在时不用 will；when 用于肯定会发生的事，if 用于可能发生的事。",
    "md": "# When I do and when I've done（when/if 从句用现在时）\n\n## ① 目标·导入\n\n记住：when/if 引导的将来从句里不用 will。\n\n## ② 规则讲解\n\n在 **when / before / after / until / as soon as / if** 引导的从句中表示将来，要用**一般现在时**（或现在完成时），不用 will。**if** 用于可能发生也可能不发生的事；**when** 用于肯定会发生的事。强调「做完之后」可用现在完成时（when I've finished）。\n\n```text\n主句 will … + when/if + 主语 + 现在时\nI'll call you when I arrive.（不是 when I will arrive）\nif = 也许    when = 肯定\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I'll call you when I arrive.** | 我到了就给你打电话。 |\n| **We'll go out when it stops raining.** | 雨停了我们出门。 |\n| **If it rains, I'll stay at home.** | 如果下雨，我就待在家里。 |\n\n## ④ 易错·对比\n\n**常见错误：when 从句里用 will**\n\n- ❌ I'll call you when I will arrive.\n- ✅ I'll call you when I arrive.\n- 原因：when/if 从句里表将来用现在时，will 只留在主句。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I'll tell him the news when he ___ back.\",\n      \"options\": [\n        \"comes\",\n        \"will come\",\n        \"came\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"when 从句里用现在时 comes，不用 will come。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I'm going out later — I'll buy bread when I ___.（肯定会出去）\",\n      \"options\": [\n        \"go out\",\n        \"will go out\",\n        \"went out\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"肯定会发生的事用 when + 现在时 go out。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"Wait here until I come back.\",\n        \"Wait here until I will come back.\",\n        \"Wait here until I came back.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"until 从句里表将来用现在时：until I come back。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n表示将来时，when/if 等从句里用现在时不用 will；when 用于肯定会发生的事，if 用于可能发生的事。\n"
  },
  {
    "id": "can-could-and-be-able-to",
    "title": "Can, could and (be) able to（能力：can、could、be able to）",
    "cefr": "A2",
    "difficulty": 2,
    "summary": "can 表能力，could 是过去式或更委婉；其他时态用 be able to；具体一次「成功做到」用 was able to。",
    "md": "# Can, could and (be) able to（能力：can、could、be able to）\n\n## ① 目标·导入\n\n学会用 can / could / be able to 表达能力和可能性。\n\n## ② 规则讲解\n\n**can** 表示能力、允许、可能；**could** 是 can 的过去式（常与 see、hear、understand 等连用），也可表示更委婉、不太确定的可能。can 只有 can/could 两种形式，其他时态用 **be able to**。过去**具体某次成功做到**用 **was/were able to / managed to**，不用 could。\n\n```text\n能力/允许：can do\n过去能力：could do / was able to do\n其他时态：will be able to / have been able to\n具体一次成功：was able to / managed to\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I can swim.** | 我会游泳。 |\n| **My grandfather could speak five languages.** | 我爷爷会说五门语言。 |\n| **The fire spread fast, but everyone was able to escape.** | 火势蔓延很快，但大家都成功逃生了。 |\n\n## ④ 易错·对比\n\n**常见错误：具体一次成功用 could**\n\n- ❌ Everybody could escape from the fire.（那次具体成功）\n- ✅ Everybody was able to escape from the fire.\n- 原因：具体某次「成功做到」用 was able to / managed to；could 表一般能力。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"She ___ play the piano very well.\",\n      \"options\": [\n        \"can\",\n        \"must\",\n        \"need\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"表示能力用 can。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「具体某一次成功做到了」该用：\",\n      \"options\": [\n        \"was able to\",\n        \"can\",\n        \"may\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"具体一次成功用 was/were able to 或 managed to。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I haven't ___ sleep well recently.\",\n      \"options\": [\n        \"been able to\",\n        \"can\",\n        \"could\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"现在完成时里 can 没法变形，要用 been able to。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\ncan 表能力，could 是过去式或更委婉；其他时态用 be able to；具体一次「成功做到」用 was able to。\n"
  },
  {
    "id": "could-do-and-could-have-done",
    "title": "Could (do) and could have (done)（could 与 could have done）",
    "cefr": "B2",
    "difficulty": 3,
    "summary": "could 提建议或表可能（比 can 不确定）；could have done 表示「过去本可以却没做」；couldn't have done 表示「不可能做过」。",
    "md": "# Could (do) and could have (done)（could 与 could have done）\n\n## ① 目标·导入\n\n分清 could do（现在/将来的可能）和 could have done（过去本可能）。\n\n## ② 规则讲解\n\n**could**：①can 的过去式；②给**建议**或表示现在/将来的**可能**，比 can 更不确定（We could go to the cinema.）。**could have done**：过去**本来可能发生却没发生**（You could have stayed with me.）。**couldn't have done**：不可能做过。\n\n```text\n建议/可能 → could do\n过去本可能（没发生）→ could have done\n不可能做过 → couldn't have done\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **We could go to the cinema tonight.** | 今晚我们可以去看电影。（建议） |\n| **You could have stayed with me!** | 你本可以住在我这儿的！（却没住） |\n| **He was lucky. He could have hurt himself.** | 他运气好，本来可能会受伤的。 |\n\n## ④ 易错·对比\n\n**常见错误：现在的具体可能用 can**\n\n- ❌ It can be true.（对眼前这件事的推测）\n- ✅ It could be true.\n- 原因：对某件具体事情说「可能是真的」，用 could 表可能。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"You ___ have told me! Why didn't you?\",\n      \"options\": [\n        \"could\",\n        \"can\",\n        \"will\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「你本可以告诉我（却没说）」是对过去的假设，用 could have done。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「今晚干点什么呢？」提个建议：We ___ go to the park.\",\n      \"options\": [\n        \"could\",\n        \"must\",\n        \"can't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"could 用来提建议，语气比 can 委婉、不确定。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"couldn't have done 表示：\",\n      \"options\": [\n        \"过去不可能做过\",\n        \"现在不能做\",\n        \"将来不会做\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"couldn't have done 表示「（当时）不可能做过」。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\ncould 提建议或表可能（比 can 不确定）；could have done 表示「过去本可以却没做」；couldn't have done 表示「不可能做过」。\n"
  },
  {
    "id": "must-and-cant",
    "title": "Must and can't（有把握的推测 must 与 can't）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "肯定推测「一定是」用 must，否定推测「不可能」用 can't（不是 mustn't）；对过去的推测用 must have done / can't have done。",
    "md": "# Must and can't（有把握的推测 must 与 can't）\n\n## ① 目标·导入\n\n学会用 must 和 can't 做有把握的推测。\n\n## ② 规则讲解\n\n很有把握地推测：**must** 表示「一定是」（You must be tired.）；**can't** 表示「不可能」（You can't be hungry already.）。对**过去**的推测用 **must have done / can't have done**。\n\n```text\n肯定推测 → must (be / be doing / have done)\n否定推测 → can't（不用 mustn't）\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **She works 12 hours a day. She must be tired.** | 她一天工作 12 小时，一定很累。 |\n| **You've just had lunch. You can't be hungry.** | 你刚吃过午饭，不可能饿。 |\n| **Nobody's at home. They must have gone out.** | 家里没人，他们肯定出门了。 |\n\n## ④ 易错·对比\n\n**常见错误：否定推测用 mustn't**\n\n- ❌ You mustn't be hungry.\n- ✅ You can't be hungry.\n- 原因：「不可能」的推测用 can't；mustn't 的意思是「禁止、不许」。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"He has been working all day. He ___ be tired.\",\n      \"options\": [\n        \"must\",\n        \"can't\",\n        \"mustn't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"累了一天，有把握地推测「一定累了」，用 must。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"She ___ be at home — all the lights are off.（推测不可能）\",\n      \"options\": [\n        \"can't\",\n        \"must\",\n        \"should\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"灯全关着，推测「不可能在家」用 can't。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「他肯定已经离开了。」= He ___ have left.\",\n      \"options\": [\n        \"must\",\n        \"can\",\n        \"will\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"对过去有把握的肯定推测用 must have done。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n肯定推测「一定是」用 must，否定推测「不可能」用 can't（不是 mustn't）；对过去的推测用 must have done / can't have done。\n"
  },
  {
    "id": "may-and-might-1",
    "title": "May and might 1（可能 may 与 might）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "may/might 表示「也许」，might 更不确定；对过去的推测用 may/might have done；maybe 是副词。",
    "md": "# May and might 1（可能 may 与 might）\n\n## ① 目标·导入\n\n学会用 may 和 might 说「也许、可能」。\n\n## ② 规则讲解\n\n**may / might** 表示「也许、可能」，might 比 may 更不确定。否定：may not / might not。对**过去**的推测用 **may/might have done**。注意：**maybe**（一个词）是副词，意思是「也许」。\n\n```text\nmay/might + 动词原形：He may be in his office.\n过去：may/might have done\nmaybe = perhaps（副词）\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **Where's Ben? He may be in his office.** | 本在哪儿？可能在办公室。 |\n| **Ask Kate. She might know.** | 问问凯特，她可能知道。 |\n| **She may have been asleep.** | 她（那时）可能在睡觉。 |\n\n## ④ 易错·对比\n\n**常见错误：may be 和 maybe 混用**\n\n- ❌ It maybe true.\n- ✅ It may be true. / Maybe it's true.\n- 原因：may be 是「情态动词 may + 动词 be」两个词；maybe 是副词，放句首修饰整句。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"Take an umbrella. It ___ rain later.\",\n      \"options\": [\n        \"might\",\n        \"must\",\n        \"can't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「之后也许会下雨」是不太确定的可能，用 might。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「也许是真的。」= It ___ be true.\",\n      \"options\": [\n        \"may\",\n        \"will\",\n        \"must\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"may 表示「也许」：It may be true。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"哪一句是正确的？\",\n      \"options\": [\n        \"It may be true.\",\n        \"It maybe true.\",\n        \"It may is true.\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"may 后接动词原形 be：It may be true。maybe 是副词，不能直接放在主语后当动词用。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nmay/might 表示「也许」，might 更不确定；对过去的推测用 may/might have done；maybe 是副词。\n"
  },
  {
    "id": "have-to-and-must",
    "title": "Have to and must（不得不与必须）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "客观「不得不」用 have to，主观看法或书面规定用 must；过去用 had to；mustn't = 禁止，don't have to = 不必。",
    "md": "# Have to and must（不得不与必须）\n\n## ① 目标·导入\n\n分清 have to（不得不）和 must（必须）。\n\n## ② 规则讲解\n\n**have to** 表示客观上的「不得不、必须」（规则、事实决定）；**must** 常表示说话人自己的看法、建议，也用于书面规定。**过去**只能用 **had to**（must 没有过去式）。have to 的疑问否定靠 do/does/did。注意区别：**mustn't**（禁止做）≠ **don't have to**（不必做）。\n\n```text\n客观必要 → have to / has to / had to\n主观看法、书面规定 → must\nmustn't = 不许    don't have to = 不必\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I have to wear glasses for reading.** | 我看书必须戴眼镜。 |\n| **You must meet him. He's great.** | 你一定要见见他，他很棒。（我的建议） |\n| **I had to leave early yesterday.** | 昨天我不得不早走。 |\n\n## ④ 易错·对比\n\n**常见错误：must 用在过去**\n\n- ❌ I must go home early yesterday.\n- ✅ I had to go home early yesterday.\n- 原因：must 没有过去式，说过去的「不得不」用 had to。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"书面规定「学生必须穿校服」：Students ___ wear uniforms.\",\n      \"options\": [\n        \"must\",\n        \"can\",\n        \"may\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"书面规则、规定常用 must。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"“I have to get up early.” 的过去式是：\",\n      \"options\": [\n        \"had to get up\",\n        \"must get up\",\n        \"have to got up\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"must 没有过去式，过去的「不得不」用 had to。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「你不必和我一起来。」= You ___ come with me.\",\n      \"options\": [\n        \"don't have to\",\n        \"mustn't\",\n        \"can't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"don't have to 表示「不必」；mustn't 是「禁止」。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n客观「不得不」用 have to，主观看法或书面规定用 must；过去用 had to；mustn't = 禁止，don't have to = 不必。\n"
  },
  {
    "id": "must-mustnt-neednt",
    "title": "Must, mustn't, needn't（必须、禁止、不必）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "must = 必须做，mustn't = 禁止做，needn't = 不必做；needn't have done 表示「做了却没必要」。",
    "md": "# Must, mustn't, needn't（必须、禁止、不必）\n\n## ① 目标·导入\n\n分清 must、mustn't、needn't 三兄弟。\n\n## ② 规则讲解\n\n**must do** = 必须做；**mustn't do** = 禁止做、不许做；**needn't do / don't need to do** = 不必做（想做也可以）。**needn't have done** = 当时做了，其实没必要（白做了）。\n\n```text\n必须 → must do\n禁止 → mustn't do\n不必 → needn't do（needn't 后不带 to）\n白做了 → needn't have done\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **You must keep it a secret.** | 这事你得保密。 |\n| **You mustn't tell anyone.** | 你不能告诉任何人。 |\n| **We needn't hurry. We have plenty of time.** | 我们不必急，时间多着呢。 |\n\n## ④ 易错·对比\n\n**常见错误：needn't 和 mustn't 混用**\n\n- ❌ You needn't tell Steve.（想表达「别告诉他」）\n- ✅ You mustn't tell Steve.\n- 原因：needn't 是「不必」（告诉也行），mustn't 才是「禁止、不许」。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"图书馆里要保持安静。You ___ make any noise.\",\n      \"options\": [\n        \"mustn't\",\n        \"needn't\",\n        \"don't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"「禁止发出噪音」用 mustn't。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"We have plenty of time. We ___ hurry.\",\n      \"options\": [\n        \"needn't\",\n        \"mustn't\",\n        \"must\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"时间充足，「不必着急」用 needn't。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"“You needn't have cooked so much food.” 的意思是：\",\n      \"options\": [\n        \"你做了这么多菜，其实没必要\",\n        \"禁止你做这么多菜\",\n        \"你必须多做些菜\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"needn't have done 表示「做了，但没必要」，常有点可惜的意味。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nmust = 必须做，mustn't = 禁止做，needn't = 不必做；needn't have done 表示「做了却没必要」。\n"
  },
  {
    "id": "should-1",
    "title": "Should 1（建议 should）",
    "cefr": "A2",
    "difficulty": 1,
    "summary": "should do 提建议「应该」，后接动词原形；should have done 表示「本该做却没做」。",
    "md": "# Should 1（建议 should）\n\n## ① 目标·导入\n\n学会用 should 提建议：「应该 / 不应该」。\n\n## ② 规则讲解\n\n**should do** = 应该做（这样做是好的），语气比 must 温和；**shouldn't do** = 不应该做。常和 I think 连用。**should have done** = 本该做却没做（遗憾、责怪）。\n\n```text\n建议：should + 动词原形（不加 to）\n否定：shouldn't do\n遗憾：should have done（本该做没做）\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **You look tired. You should go to bed.** | 你看起来很累，应该去睡了。 |\n| **You shouldn't eat too much candy.** | 你不该吃太多糖。 |\n| **You should have come to the party.** | 你本该来参加聚会的。（可惜没来） |\n\n## ④ 易错·对比\n\n**常见错误：should 后加 to**\n\n- ❌ You should to go now.\n- ✅ You should go now.\n- 原因：should 是情态动词，后接动词原形，不加 to。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"You should ___ more water every day.\",\n      \"options\": [\n        \"drink\",\n        \"to drink\",\n        \"drinking\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"should 后接动词原形：should drink。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我感冒了。」朋友给建议：You ___ see a doctor.\",\n      \"options\": [\n        \"should\",\n        \"mustn't\",\n        \"needn't\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"提建议「应该看医生」用 should。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"should have done 表示：\",\n      \"options\": [\n        \"本该做却没做\",\n        \"必须现在做\",\n        \"禁止做\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"You should have come. = 你本该来的（没来）。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nshould do 提建议「应该」，后接动词原形；should have done 表示「本该做却没做」。\n"
  },
  {
    "id": "id-better-its-time",
    "title": "I'd better… It's time…（最好……；该……了）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "had better do 表示「最好做，否则有麻烦」，不带 to；It's time + 过去式表示「早该……了」。",
    "md": "# I'd better… It's time…（最好……；该……了）\n\n## ① 目标·导入\n\n学会用 had better 和 It's time… 表达「最好……」「该……了」。\n\n## ② 规则讲解\n\n**had better do**（'d better）= 最好做，否则会有麻烦，比 should 语气重，用于**具体某次**情况，后接动词原形（不带 to）。**It's time (for sb) to do** = 该做某事了；**It's time + 主语 + 过去式** = 「早该……了」，常带抱怨语气（形式是过去式，意思是现在）。\n\n```text\n最好 → had better do（'d = had）\n该……了 → It's time to do\n早该……了 → It's time + 主语 + 过去式\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **I'd better go now, or I'll be late.** | 我最好现在走，不然会迟到。 |\n| **It's time to go home.** | 该回家了。 |\n| **It's time you went to bed.** | 你早该去睡觉了。 |\n\n## ④ 易错·对比\n\n**常见错误：had better 后加 to**\n\n- ❌ I'd better to go.\n- ✅ I'd better go.\n- 原因：had better 后接动词原形，不带 to。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"It might rain. You'd better ___ an umbrella.\",\n      \"options\": [\n        \"take\",\n        \"to take\",\n        \"taking\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"had better 后接动词原形：'d better take。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「你早该写作业了。」= It's time you ___ your homework.\",\n      \"options\": [\n        \"did\",\n        \"do\",\n        \"will do\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"It's time + 主语 + 过去式，表示「早该做了」，带抱怨语气。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I'd better 中的 'd 是哪个词的缩写？\",\n      \"options\": [\n        \"had\",\n        \"would\",\n        \"will\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"'d better = had better，虽然 had 是过去形式，但说的是现在或将来的事。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nhad better do 表示「最好做，否则有麻烦」，不带 to；It's time + 过去式表示「早该……了」。\n"
  },
  {
    "id": "would",
    "title": "Would（想象的世界 would）",
    "cefr": "B1",
    "difficulty": 2,
    "summary": "would 描述想象的、非真实的情况；would have done 想象过去；也可表示过去的习惯或「拒绝」（wouldn't）。",
    "md": "# Would（想象的世界 would）\n\n## ① 目标·导入\n\n学会用 would 谈论「想象中会……」的情况。\n\n## ② 规则讲解\n\n**would ('d) / wouldn't** 描述**想象的、非真实**的情况（I'd love to live by the sea.）。**would have done** 想象过去没发生的事（You would have liked the film.）。would 常和 if 连用；有时表示**过去的习惯**（类似 used to）；wouldn't 还可表示「（怎么也不）肯、拒绝」。\n\n```text\n想象现在 → would do\n想象过去 → would have done\n过去习惯 → would do（类似 used to）\n拒绝 → wouldn't do\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **It would be nice to have a dog.** | 有只狗就好了。 |\n| **I would have called you, but I didn't have your number.** | 我本想给你打电话的，可是没有你的号码。 |\n| **When we were kids, we would play by the river.** | 小时候我们常在河边玩。 |\n\n## ④ 易错·对比\n\n**常见错误：will 和 would 不分**\n\n- ❌ I'll stay longer, but I have to go.（前后矛盾）\n- ✅ I'd stay longer, but I have to go.\n- 原因：真的能留用 will；想留却不能留，是想象，用 would。\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"I ___ love to visit Paris one day.\",\n      \"options\": [\n        \"would\",\n        \"do\",\n        \"did\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"would love to 表示想象、愿望「很想去」。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"「我本想帮你的（没能帮上）。」= I ___ have helped you.\",\n      \"options\": [\n        \"would\",\n        \"will\",\n        \"do\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"对过去没发生的事的想象用 would have done。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"“The car wouldn't start.” 里的 wouldn't 表示：\",\n      \"options\": [\n        \"怎么也不肯、拒绝启动\",\n        \"必须启动\",\n        \"已经启动\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"wouldn't 可以表示「拒绝、不肯」，这里说车「就是打不着火」。\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\nwould 描述想象的、非真实的情况；would have done 想象过去；也可表示过去的习惯或「拒绝」（wouldn't）。\n"
  },
  {
    "id": "can-could-would-you-etc-requests-offers-permission-and-invitations",
    "title": "Can/could/would you…?（请求、提议、允许与邀请）",
    "cefr": "A2",
    "difficulty": 1,
    "summary": "请人帮忙用 Could you…?，请求允许用 Could/May I…?，提议邀请用 Would you like…?",
    "md": "# Can/could/would you…?（请求、提议、允许与邀请）\n\n## ① 目标·导入\n\n学会用 can/could/would 礼貌地请求、提议、征求允许和发出邀请。\n\n## ② 规则讲解\n\n请人帮忙：**Can/Could you…?**（could 更客气）。要东西：**Can/Could I have…?**。请求允许：**Can/Could/May I…?**（may 最正式）。提议、邀请：**Would you like…?**（不说 Do you like）。询问是否介意：**Do you mind if I…?**\n\n```text\n请人帮忙 → Could you …, please?\n请求允许 → Could/May I …?\n提议邀请 → Would you like …?\n```\n\n## ③ 例句库\n\n| 英文 | 中文 |\n| --- | --- |\n| **Could you open the door, please?** | 能帮我开下门吗？ |\n| **Can I have some water, please?** | 请给我点水好吗？ |\n| **Would you like some coffee?** | 你想来点咖啡吗？ |\n\n## ④ 易错·对比\n\n**常见错误：当场提议用 Do you like**\n\n- ❌ Do you like some coffee?（现在请对方喝）\n- ✅ Would you like some coffee?\n- 原因：Do you like…? 是问平时的喜好；当场提议、邀请要用 Would you like…?\n\n## ⑤ 即时练习\n\n做一做下面 3 道题，马上看对错。\n\n```quiz\n{\n  \"questions\": [\n    {\n      \"type\": \"choice\",\n      \"stem\": \"礼貌地请别人帮忙：___ you help me, please?\",\n      \"options\": [\n        \"Could\",\n        \"Must\",\n        \"Should\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"请求帮助用 Can/Could you…?，could 更客气。\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"请对方喝咖啡（提议）：___ you like some coffee?\",\n      \"options\": [\n        \"Would\",\n        \"Do\",\n        \"Are\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"提议、邀请用 Would you like…?\"\n    },\n    {\n      \"type\": \"choice\",\n      \"stem\": \"请求允许用一下别人的笔：___ I use your pen?\",\n      \"options\": [\n        \"Could\",\n        \"Must\",\n        \"Will\"\n      ],\n      \"answer\": 0,\n      \"explain\": \"请求允许用 Can/Could/May I…?\"\n    }\n  ]\n}\n```\n\n## ⑥ 小结·知识卡\n\n请人帮忙用 Could you…?，请求允许用 Could/May I…?，提议邀请用 Would you like…?\n"
  }
]