07-01
Ability
能力💡 概念 Concept
can = present ability; could = past ability; be able to = any tense or for achievements.can 表现在能力；could 表过去能力；be able to 可用于任何时态或表示成功做到。
📐 规则 Rules
现在
can + base: I can swim.
can + 原形：我会游泳。
过去
could + base: When I was young, I could run fast.
could + 原形：年轻时我能跑很快。
成功做到
was/were able to for specific achievements: I was able to finish on time.
具体成功做到用 was able to：我按时完成了。
✏️ 例句 Examples
She can speak three languages.
她会说三种语言。
He couldn't swim until he was ten.
他十岁才会游泳。
They were able to escape the fire.
他们成功逃离了火灾。
⚠️ 常见错误 Common Mistakes
❌ She can to swim → modal + base, no to.❌ 情态动词后接原形，不加 to。
❌ I can swims → modal + base form.❌ 情态动词后动词用原形。
07-02
Permission
许可💡 概念 Concept
can = informal permission; may = formal permission; could = polite request; be allowed to = other tenses.can 非正式许可；may 正式许可；could 礼貌请求；be allowed to 用于其他时态。
📐 规则 Rules
非正式
Can I go out?
我能出去吗？（口语）
正式
May I come in?
我可以进来吗？（正式）
礼貌
Could I borrow your pen?
我能借用你的笔吗？（更礼貌）
其他时态
You will be allowed to enter later.
稍后你会被允许进入。
✏️ 例句 Examples
Can I use your phone?
我能用你的电话吗？
May I ask a question?
我可以问个问题吗？
Students are allowed to use the library.
学生可以使用图书馆。
⚠️ 常见错误 Common Mistakes
❌ May I... in very informal speech can sound stiff — can is fine among friends.❌ 朋友之间用 can 更自然。
❌ I am allowed to go yesterday → use was allowed to.❌ 过去时用 was allowed to。
07-03
Obligation
义务💡 概念 Concept
must = strong obligation (internal/rule); have to = external necessity; should/ought to = advice; mustn't = prohibition; don't have to = not necessary.must 表强烈义务（内部/规则）；have to 表外部必要性；should/ought to 表建议；mustn't 表禁止；don't have to 表不必。
📐 规则 Rules
must
You must wear a seatbelt.
你必须系安全带。
have to
I have to work on Saturdays.
我周六必须上班。
should
You should drink more water.
你应该多喝水。
禁止 vs 不必
You mustn't smoke here. / You don't have to come.
禁止：你不能在这里抽烟。不必：你不必来。
✏️ 例句 Examples
You must finish your homework before playing.
你必须先完成作业再玩。
She has to wear a uniform at work.
她上班必须穿制服。
You ought to see a doctor.
你应该去看医生。
⚠️ 常见错误 Common Mistakes
❌ You don't have to = no obligation (optional), NOT prohibition.❌ don't have to 表【不必】，不是【禁止】。
❌ must not vs don't have to — different meanings!❌ mustn't（禁止）与 don't have to（不必）意思不同。
07-04
Probability
可能性💡 概念 Concept
Deduction about the present: must = almost certain; might/may/could = possible; can't = impossible/almost certainly not.对现在的推断：must 几乎确定；might/may/could 可能；can't 不可能。
📐 规则 Rules
几乎确定
must + base: She has a key, so she must be the owner.
must + 原形：她肯定就是主人。
可能
might/may/could: He might be at home now.
might/may/could：他现在可能在家。
不可能
can't + base: That can't be true!
can't + 原形：那不可能是真的！
✏️ 例句 Examples
The lights are on, so she must be home.
灯亮着，所以她一定在家。
It might rain later.
稍后可能会下雨。
He can't be 40 — he looks so young!
他不可能是40岁——他看起来太年轻了！
⚠️ 常见错误 Common Mistakes
❌ mustn't for deduction → use can't: He can't be at home.❌ 否定推断用 can't，不用 mustn't。
❌ may not = possibly not, NOT prohibition.❌ may not 表【可能不】，不是禁止。
07-05
Past Modals
过去情态💡 概念 Concept
modal + have + past participle for the past: could have (possibility), should have (regret/criticism), must have (certainty), might have (guess), can't have (impossible).情态动词 + have + 过去分词表过去：could have 可能、should have 本应、must have 一定、might have 也许、can't have 不可能。
📐 规则 Rules
must have
certainty: She must have left early.
一定：她一定早就离开了。
should have
regret: I should have studied harder.
本应：我本该更用功。
could have
possibility: He could have been hurt.
可能：他可能受伤了。
can't have
impossibility: He can't have seen us.
不可能：他不可能看到我们。
✏️ 例句 Examples
You must have been tired after the trip.
旅行后你一定很累。
She should have called me.
她本应给我打电话。
They might have missed the bus.
他们可能错过了公交车。
⚠️ 常见错误 Common Mistakes
❌ She must left early → modal + have + pp: must have left.❌ 过去情态结构是 must have + 过去分词。
❌ I should studied → should have studied.❌ 漏掉 have。
07-06
Requests and Offers
请求与提议💡 概念 Concept
Requests: Can/Could/Would you...? Offers: Shall I...? / Can I...? / Would you like...?请求：Can/Could/Would you...? 提议：Shall I...? / Can I...? / Would you like...?
📐 规则 Rules
请求
Could you open the door, please? (polite)
请把门打开好吗？（礼貌）
提议帮助
Shall I carry your bag?
要我帮你拿包吗？
邀请
Would you like some tea?
要来点茶吗？
✏️ 例句 Examples
Can you help me with this box?
你能帮我搬这个箱子吗？
Shall I turn on the light?
要我开灯吗？
Would you like to join us?
你愿意加入我们吗？
⚠️ 常见错误 Common Mistakes
❌ Do you want I help? → correct: Shall I help?❌ 提议帮助用 Shall I...?
❌ Give me the book (too direct) → Could you give me the book?❌ 请求更礼貌的说法。
07-07
Modal Contrast
情态动词对比💡 概念 Concept
Choose the modal by meaning: ability (can), permission (may), obligation (must), advice (should), possibility (might), certainty (must/can't).按含义选情态动词：能力 can、许可 may、义务 must、建议 should、可能 might、确定 must/can't。
📐 规则 Rules
强度排序
can't < might < could < may < must (certainty scale)
可能性从低到高：can't < might < could < may < must
语境决定
Same modal, different job: Can you swim? (ability) / Can I leave? (permission) / It can rain here. (possibility)
同一个 can 在不同语境功能不同。
✏️ 例句 Examples
You must be joking! (certainty — deduction)
你一定在开玩笑！（确定推断）
We might visit them next week. (possibility)
我们下周可能会去拜访他们。（可能）
Everyone should recycle. (advice/general rule)
每个人都应该回收利用。（建议）
⚠️ 常见错误 Common Mistakes
❌ Using must for advice → must is strong obligation; use should for suggestions.❌ 建议用 should，不用 must。
❌ Using can't for 'not allowed' vs 'impossible' — check context.❌ 分清 can't 表「不允许」还是「不可能」。
07-08
Production and Editing
综合运用与改错💡 概念 Concept
In real scenarios, identify the function (ability, permission, obligation, advice, possibility) and pick the modal, then check the form: modal + base verb.在实际场景中先判断功能（能力、许可、义务、建议、可能），再选情态动词，最后检查形式：情态动词 + 动词原形。
📐 规则 Rules
功能优先
What is the speaker doing? Asking permission, giving advice, making a deduction?
说话人在做什么：请求许可、给建议、作推断？
形式检查
modal + base (no -s, no to): She must go.
情态动词 + 原形（不加 -s、不加 to）。
过去式
For past meaning: modal + have + pp.
表过去：情态动词 + have + 过去分词。
✏️ 例句 Examples
You look pale — you should rest.
你脸色不好——应该休息一下。
Passengers must fasten their seatbelts.
乘客必须系好安全带。
She can't have forgotten — we reminded her twice.
她不可能忘了——我们提醒过她两次。
⚠️ 常见错误 Common Mistakes
❌ He can sings → modal + base: He can sing.❌ 情态动词后动词用原形。
❌ You must to go → no to after modals.❌ 情态动词后不加 to。
PR
课堂练习 Practice
选自 GramLingo 题库Q1She ___ swim when she was five years old.
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Q2She is not here. She ___ be at home.
点击选项上方文字已展开答案 · 正确答案由 GramLingo 题库提供
Q3Choose the correct sentence:
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