威威老師的文法特快車：助動詞詳解 (Modal Verbs)
課程導航
哈囉各位同學！我是威威老師。
來，看下面三句的差異：
- “He must have forgotten.”
- “He should have remembered.”
- “He could have known.”
中文都跟「他…的」有關——但意思天差地遠！
- must have = 一定忘了（很肯定的過去推測）
- should have = 本來應該記得（遺憾，沒記得）
- could have = 本來可以知道（惋惜的可能性）
英文的助動詞 + have + V-pp，是評論過去事件的精密工具——學測、多益、TOEFL 超愛考！上一章 11 基本助動詞 你打了基礎；今天我們進入進階用法：
8 大助動詞 × 過去推測 × used to 三胞胎 × 各種陷阱——一次解決！
繫好安全帶 🚂
課前快問 (Pre-Quiz) — 複習 19 進階時式
- By the time we arrived, the movie ____ (begin) for half an hour.
- 改錯：I have studied English since five years.
- She ____ (work) at this company for ten years before she retired.
解答
- had begun / had been beginning（過去完成）
- for five years（since 接時間點，for 接時間長度）
- had worked / had been working（過去完成 / 過去完成進行）
一、助動詞的 4 大鐵律
助動詞跟普通動詞 完全不一樣！
| 鐵律 | 規則 | 範例 |
|---|---|---|
| 1. 後接原形 VR | 助動詞 + 原形動詞 | She can swim.（不是 swims） |
| 2. 沒有人稱變化 | 不分主詞，永遠一樣 | He can, She can, They can（沒有 cans） |
| 3. 否定直接加 not | 不需要 do/does | She cannot swim.（不是 doesn’t can） |
| 4. 疑問句直接倒裝 | 助動詞前移 | Can she swim?（不是 Does she can） |
💡 威威核心：助動詞自己就是「特種部隊」——獨立行事，不需要 do 哥當保鑣。
二、can / could
2-1 can — 能力、許可、可能性
| 用法 | 例句 |
|---|---|
| 能力 | I can swim.（我會游泳） |
| 許可（口語） | Can I borrow your pen? |
| 可能性 | It can get cold here.（一般可能性） |
2-2 could — 過去能力、禮貌、假設
| 用法 | 例句 |
|---|---|
| 過去能力 | I could swim at age 5. |
| 禮貌請求 | Could you help me?（比 can 更禮貌） |
| 假設語氣 | If I had time, I could travel. |
2-3 ⚠️ can vs. be able to（時態問題！）
can 沒有未來式和完成式！需要 be able to 代替！
| 時態 | can ✗ | be able to ✓ |
|---|---|---|
| 未來 | ❌ will can | ✅ will be able to |
| 完成式 | ❌ have can | ✅ have been able to |
2-4 can’t — 強烈否定推測
| 例句 | 意思 |
|---|---|
| He can’t be serious. | 他不可能是認真的 |
| She can’t have done it. | 她不可能做了這件事 |
🎯 can/could 即時練習（5 題）
1. Choose: I ______ swim when I was 5. (A) can (B) could (C) may (D) should
2. 改錯：He will can finish the work tomorrow.
3. Choose: ______ you please pass me the salt? (A) Can (B) May (C) Could (D) Both A and C
4. Choose: He ______ be the thief. He was with me! (A) must (B) can’t (C) should (D) may
5. Translate: 「五年後我將能說流利的中文。」(Use will be able to)
寫好答案再往下看 👇
解答與詳解
第 1 題：(B) could
過去能力 → could。
第 2 題：will can → will be able to
✅ He will be able to finish.（兩助動詞不能連用，can 沒未來式）
第 3 題：(D) Both A and C
Can/Could you pass…? 都對，Could 更禮貌。
第 4 題：(B) can't
「不可能」→ can’t。
第 5 題：In five years, I will be able to speak Chinese fluently.
三、may / might — 許可、可能性、推測
3-1 may — 正式許可、可能性
| 用法 | 例句 |
|---|---|
| 正式許可 | May I come in? |
| 可能性 (~50%) | She may be at home. |
| 祝福 | May you have a great year! |
3-2 might — 較不確定的可能性
| 用法 | 例句 |
|---|---|
| 可能性 (~30%) | It might rain. |
| 禮貌建議 | You might want to try this. |
3-3 may / might + have + V-pp — 過去推測
| 句型 | 把握度 | 例句 |
|---|---|---|
| may have + V-pp | ~50% | He may have missed the bus. |
| might have + V-pp | ~30% | She might have forgotten. |
🎯 may/might 即時練習（5 題）
1. Choose: It ______ snow this weekend. (A) shall (B) must (C) might (D) ought
2. Choose: She didn’t answer. She ______ be busy. (A) may (B) shall (C) ought (D) used
3. Choose: He ______ have forgotten the meeting. (A) might (B) shall (C) used (D) will
4. Translate: 「他可能忘了我的生日。」(Use may have)
5. Choose: ______ I borrow your pen, please?（最正式） (A) Can (B) Could (C) May (D) Will
寫好答案再往下看 👇
解答與詳解
第 1 題：(C) might
不確定可能性 → might。
第 2 題：(A) may
「可能在忙」→ may（也可 might）。
第 3 題：(A) might
過去推測 → might have。
第 4 題：He may have forgotten my birthday.
第 5 題：(C) May
最正式 → May I。
四、must / have to — 義務、必要、推測
4-1 must vs. have to
| must | have to | |
|---|---|---|
| 來源 | 內在/主觀 | 外在/客觀 |
| 語氣 | 強烈 | 客觀 |
| 時態 | 沒過去式 | 有 had to / will have to |
| 例句 | I must lose weight.（自我決心） | I have to wear glasses.（醫囑） |
4-2 ⚠️ 否定意思完全不同！
| 否定 | 意思 |
|---|---|
| must not (mustn’t) | 禁止！不可以！ |
| don’t have to | 不必（不是禁止） |
🚨 超經典陷阱！
- You mustn’t smoke here. = 禁止吸煙！
- You don’t have to come. = 不必來（可選擇）
4-3 must — 強烈推測
| 例句 | 意思 |
|---|---|
| He must be tired. | 他一定累了（看起來累） |
| She must have forgotten. | 她一定忘了 |
4-4 推測強度排行
must (~95%) > should (~75%) > may/might (~50%) > can't (~0%, 不可能)
4-5 must / can’t + have + V-pp — 過去推測
| 句型 | 把握度 | 例句 |
|---|---|---|
| must have + V-pp | ~95%（一定做了） | He must have forgotten. |
| can’t have + V-pp | ~95%（不可能做了） | She can’t have left. Her car is here. |
💎 must have 的否定不是 mustn’t have，而是 can’t have！
🎯 must/have to 即時練習（5 題）
1. Choose: You ______ smoke here.（禁止） (A) don’t have to (B) mustn’t (C) needn’t (D) couldn’t
2. Choose: You ______ come if you’re busy.（不必） (A) mustn’t (B) shouldn’t (C) don’t have to (D) can’t
3. Choose: She ______ be Mary. I just saw Mary downstairs. (A) must (B) can’t (C) should (D) may
4. Translate: 「他一定是累了。」(Use must be)
5. Choose: He ______ have done it. He’s been with me all day. (A) must (B) can’t (C) should (D) may
寫好答案再往下看 👇
解答與詳解
第 1 題：(B) mustn't
禁止 → mustn’t。
第 2 題：(C) don't have to
不必 → don’t have to。
第 3 題：(B) can't
不可能（剛在樓下看到 Mary）→ can’t。
第 4 題：He must be tired.
第 5 題：(B) can't
不可能（整天跟我在一起）→ can’t have done。
五、should / ought to — 應該、建議、遺憾
5-1 should — 應該、預期、建議
| 用法 | 例句 |
|---|---|
| 建議 | You should see a doctor. |
| 預期 | The bus should be here by now. |
5-2 ought to = should（更正式）
“You ought to apologize.” = “You should apologize.”
5-3 ⭐ should have + V-pp — 「本來應該（但沒做）」遺憾！
| 句型 | 意思 | 例句 |
|---|---|---|
| should have + V-pp | 當初應該做（沒做） | I should have studied harder. |
| shouldn’t have + V-pp | 當初不該做（卻做了） | You shouldn’t have spent so much. |
💎 should have + V-pp 是學測超高頻考點！ 表達「遺憾／後悔」——「早知道就…」
5-4 生活情境
考試考砸 → "I should have studied harder."（早知道就多讀）
遲到了 → "I should have left earlier."（早知道就早點出門）
朋友送驚喜 → "Oh, you shouldn't have!"（你太客氣了，不用這樣）
🎯 should 即時練習（5 題）
1. Choose: You look tired. You ______ go to bed earlier. (A) must (B) should (C) might (D) can
2. Choose: I ______ harder for the exam.（後悔沒讀） (A) should study (B) should have studied (C) must study (D) had to study
3. Translate: 「你不該對她說那種話。」(Use shouldn’t have)
4. Choose: He’s not here yet. He ______ have missed the train. (A) should (B) might (C) ought (D) can’t
5. Choose: You ______ wear a seatbelt while driving. (A) should (B) ought to (C) Both A and B (D) Neither
寫好答案再往下看 👇
解答與詳解
第 1 題：(B) should
建議 → should。
第 2 題：(B) should have studied
後悔沒讀 → should have + V-pp。
第 3 題：You shouldn't have said that to her.
第 4 題：(B) might
不確定推測 → might have（should 在這裡語意較弱）。
第 5 題：(C) Both A and B
should = ought to，都對。
六、will / would — 未來、意願、過去習慣、假設
6-1 will
| 用法 | 例句 |
|---|---|
| 未來 | It will rain tomorrow. |
| 意願 | I will help you. |
| 承諾 | I will never give up. |
| 拒絕（won’t） | He won’t listen. |
6-2 would
| 用法 | 例句 |
|---|---|
| 過去習慣 | When young, I would play outside. |
| 禮貌請求 | Would you like coffee? |
| 假設語氣 | If I were you, I would go. |
6-3 ⭐ would have + V-pp — 「本來會（但沒做）」
| 例句 | 中文 |
|---|---|
| I would have helped, but I didn’t know. | 本來會幫，但我不知道。 |
| She would have come, but she was sick. | 本來會來，但她生病了。 |
💡 would have + V-pp 常搭配 but 說明沒做的原因。
🎯 will/would 即時練習（5 題）
1. Choose: I ______ rather stay home tonight. (A) will (B) would (C) had (D) should
2. Choose: When I was young, I ______ play in the park every day. (A) used to (B) would (C) Both A and B (D) will
3. Translate: 「我本來會幫你，但我不知道你需要幫忙。」(Use would have + but)
4. Choose: ______ you mind opening the window? (A) Will (B) Would (C) Should (D) Could
5. Choose: He ______ have won if he hadn’t fallen. (A) will (B) would (C) should (D) must
寫好答案再往下看 👇
解答與詳解
第 1 題：(B) would
would rather = 寧願。
第 2 題：(C) Both A and B
used to + VR / would + VR 都可表過去習慣（would 較文學）。
第 3 題：I would have helped you, but I didn't know you needed help.
第 4 題：(B) Would
Would you mind…? 是禮貌的請求。
第 5 題：(B) would
假設 → would have + V-pp。
七、shall + used to 三胞胎（必背！）
7-1 shall
| 用法 | 例句 |
|---|---|
| 提議 | Shall we go now? |
| 徵求意見 | Shall I open the window? |
| 法律/正式 | The tenant shall pay rent on time. |
7-2 ⭐ used to 三胞胎 — 學測超經典陷阱！
| used to + VR | be used to + V-ing | be used to + VR | |
|---|---|---|---|
| 意思 | 過去常常（現在不了） | 習慣於… | 被用來…（被動） |
| 結構 | used to + 原形 | be + used to + V-ing | be + used to + 原形 |
| 例句 | I used to smoke. | I am used to getting up early. | Wood is used to make paper. |
| 時態 | 只過去 | 任何時態 | 任何時態 |
7-3 三者對比範例
| 句型 | 例句 | 中文 |
|---|---|---|
| used to + VR | I used to play basketball every weekend. | 我以前每週末打籃球（現在不了） |
| be used to + V-ing | I am used to getting up early. | 我習慣早起 |
| be used to + VR | Wood is used to make paper. | 木材被用來造紙 |
🚨 關鍵判斷：
- 後接 V-ing → be used to（習慣於）
- 後接 VR + 沒 be → used to（過去常常）
- 後接 VR + 有 be → be used to（被用來）
🎯 used to 三胞胎即時練習（5 題）
1. Fill in: I ______ (use) live in Tainan when I was a child.
2. Fill in: I am used to ______ (work) late.
3. Fill in: This room is used to ______ (store) old furniture.
4. 改錯：She is used to drink coffee every morning.
5. Translate: 「我以前喜歡甜食，但現在習慣了無糖飲食。」(Use used to + be used to)
寫好答案再往下看 👇
解答與詳解
第 1 題：used to
✅ I used to live in Tainan.（過去常住 + VR）
第 2 題：working
✅ I am used to working late.（習慣於 + V-ing）
第 3 題：store
✅ This room is used to store old furniture.（被用來 + 原形）
第 4 題：drink → drinking
✅ She is used to drinking coffee.（be used to + V-ing）
第 5 題：I used to like sweets, but now I am used to a sugar-free diet.
八、助動詞 + have + V-pp — 完整總整理
8-1 推測類（評論過去）
| 句型 | 把握度 | 例句 |
|---|---|---|
| must have + V-pp | ~95% 一定做了 | He must have forgotten. |
| can’t have + V-pp | ~95% 不可能做了 | She can’t have left. |
| may have + V-pp | ~50% 可能做了 | He may have missed the bus. |
| might have + V-pp | ~30% 或許做了 | She might have gone home. |
8-2 遺憾類（本來…但…）
| 句型 | 意思 | 例句 |
|---|---|---|
| should have + V-pp | 本應做（沒做） | I should have prepared better. |
| shouldn’t have + V-pp | 本不該做（卻做了） | You shouldn’t have spent so much. |
| could have + V-pp | 本來可以（沒做） | I could have won, but I was careless. |
| would have + V-pp | 本來會（沒發生） | I would have helped, but I didn’t know. |
🎯 威威分類記法：
- 推測類：must / can’t / may / might + have + V-pp
- 遺憾類：should / shouldn’t / could / would + have + V-pp
🎯 助動詞 + have + V-pp 即時練習（5 題）
1. Choose: You ______ me earlier. I could have helped. (A) should tell (B) should have told (C) must tell (D) had to tell
2. Choose: The lights are off. They ______ to bed already. (A) must go (B) should go (C) must have gone (D) should have gone
3. Choose: He ______ have done it. He was at home all day. (A) must (B) can’t (C) should (D) would
4. Translate: 「她可能已經離開了。」(Use may have)
5. Choose: I ______ have won the game, but I made too many mistakes. (A) must (B) should (C) could (D) might
寫好答案再往下看 👇
解答與詳解
第 1 題：(B) should have told
「當初應該告訴」→ should have + V-pp。
第 2 題：(C) must have gone
「燈關了，一定睡了」→ must have + V-pp。
第 3 題：(B) can't
不可能（整天在家）→ can’t have done。
第 4 題：She may have already left.
第 5 題：(C) could
「本來可以贏（但失誤太多）」→ could have + V-pp。
九、考試陷阱大整理
學測助動詞考題的 6 大陷阱
陷阱 1：mustn’t vs. don’t have to
mustn’t = 禁止；don’t have to = 不必。意思相反！
陷阱 2：must have V-pp 的否定 = can’t have V-pp（不是 mustn’t have）
陷阱 3：助動詞後接原形
❌ should studying → ✅ should study
陷阱 4：兩助動詞不能連用
❌ will can → ✅ will be able to
陷阱 5：used to 三胞胎
看後面接 VR/V-ing + 有沒有 be 來判斷！
陷阱 6：should have + V-pp（遺憾）
學測超高頻！表達「當初應該…但沒做」。
章末總測驗 (Chapter Test) — 30 題
🟢 基礎題 (1-10)
1. You ______ drive without a license.（禁止） (A) must not (B) don’t have to (C) needn’t (D) couldn’t
2. ______ I borrow your dictionary?（最禮貌） (A) Will (B) Should (C) Must (D) May
3. She ______ speak three languages. (A) can (B) must (C) should (D) may
4. You ______ wear a seatbelt while driving. (A) should (B) might (C) will (D) could
5. I ______ play piano when I was young, but I can’t now. (A) could (B) should (C) might (D) would
6. It ______ rain later. Look at those clouds. (A) must (B) shall (C) may (D) ought
7. ______ we go for dinner tonight? (A) Shall (B) Will (C) Must (D) Have
8. I am used to ______ (get) up early every morning.
9. He ______ have finished the report. He’s still working on it. (A) can’t (B) mustn’t (C) shouldn’t (D) won’t
10. You ______ enter the restricted area. (A) must not (B) don’t have to (C) shouldn’t (D) won’t
🟡 進階題 (11-20)
11. I ______ the exam, but I didn’t study enough. (A) could pass (B) could have passed (C) can pass (D) must have passed
12. Fill in: She ______ (should, tell) him the truth earlier.
13. Choose: Wood ______ to build houses. (A) is used (B) used to (C) is used to (D) uses to
14. 改錯：He must has left his phone at home.
15. Choose: You look exhausted. You ______ worked all night. (A) must have (B) should have (C) can have (D) may not have
16. Fill in: I ______ (use to) live in the countryside as a child.
17. Choose: She ______ been more careful. The vase is broken now. (A) should have (B) must have (C) can’t have (D) would have
18. Translate: 「你必須交稅。」(法律規定，用 have to)
19. Choose: If I had more money, I ______ buy a car. (A) will (B) would (C) can (D) should
20. 改錯：You don’t must worry about the test.
🔴 挑戰題 (21-30)
21. Choose: He ______ on time, but his car broke down. (A) should arrive (B) should have arrived (C) must arrive (D) can arrive
22. Choose all correct: (A) I used to smoke, but I quit. (B) She is used to work late every night. (C) He must have been tired after the marathon. (D) You must not park here. (E) She could have won if she hadn’t fallen.
23. Translate: 「他不可能已經到家了，他十分鐘前才走。」(Use can’t have)
24. Choose: You ______ finished all the work? Amazing! (A) must have (B) should have (C) can’t have (D) might have
25. Fill in: (a) I ______ (以前常) eat fast food. (b) I ______ (習慣於) cooking at home now. (c) This kitchen ______ (被用來) prepare meals.
26. Translate three sentences: (a) 「她一定還在睡覺。」(Use must) (b) 「我當初應該更努力的。」(Use should have) (c) 「他可能會晚點到。」(Use might)
27. Find errors: (a) “He cans speak Chinese.” (b) “You musts go now.” (c) “I will can finish tomorrow.” (d) “She is used to drink coffee.”
28. Choose: ______ I help you with that? (A) Shall (B) Will (C) Must (D) Should
29. Translate: (a) 「我寧願步行也不要搭車。」(Use would rather) (b) 「我們以前每年都去日本。」(Use used to) (c) 「她當初不該那樣說的。」(Use shouldn’t have)
30. Terminal challenge—rewrite fixing all errors: “You musts study harder. You don’t must waste time. You are used to play video games every night, but you must to change. Last year, I should studied more, but I didn’t. If I had studied, I will pass the exam. You must to learn from my mistake.”
章末總測驗 解答與詳解
🟢 基礎題 解答
第 1 題：(A) must not — 禁止無照駕駛。
第 2 題：(D) May — 最正式請求。
第 3 題：(A) can — 能力。
第 4 題：(A) should — 建議。
第 5 題：(A) could — 過去能力。
第 6 題：(C) may — 可能性（看到雲）。
第 7 題：(A) Shall — 提議「...好嗎？」。
第 8 題：getting — be used to + V-ing。
第 9 題：(A) can't — 不可能（還在工作）→ can't have。
第 10 題：(A) must not — 禁止進入。
🟡 進階題 解答
第 11 題：(B) could have passed
「本來可以通過（但沒讀夠）」→ could have + V-pp。
第 12 題：should have told
「當初應該告訴」→ should have + V-pp。
第 13 題：(A) is used
「被用來蓋房子」→ 被動 is used to + VR。
第 14 題：has → have
✅ He must have left（助動詞後接原形 have，不是 has）。
第 15 題：(A) must have
「一定熬夜」→ 強烈推測。
第 16 題：used to
過去習慣 + VR。
第 17 題：(A) should have
「當初應該更小心」→ 遺憾。
第 18 題：You have to pay taxes.
法律規定 → have to（也可 must）。
第 19 題：(B) would
假設語氣。
第 20 題：don't must → don't have to
✅ You don’t have to worry.（不必）。don’t + must 不存在！
🔴 挑戰題 解答
第 21 題：(B) should have arrived
「本應準時（但車拋錨）」→ 遺憾。
第 22 題：(A)(C)(D)(E)
(B) ✗ She is used to work → working（V-ing）。 (A)(C)(D)(E) 都對。
第 23 題：He can't have arrived home yet. He only left ten minutes ago.
第 24 題：(A) must have
驚訝肯定推測 → must have。
第 25 題：
(a) used to eat (b) am used to cooking (c) is used to prepare
第 26 題：翻譯
(a) She must still be sleeping. (b) I should have worked harder. (c) He might arrive late.
第 27 題：找錯
(a) cans → can（沒三單） (b) musts → must（沒三單） (c) will can → will be able to（兩助動詞不能連用） (d) drink → drinking（be used to + V-ing）
第 28 題：(A) Shall
Shall I help you…? 是徵求意見的禮貌句型。
第 29 題：翻譯
(a) I would rather walk than take a bus. (b) We used to go to Japan every year. (c) She shouldn’t have said that.
第 30 題：完整修正
原段：You musts study. You don’t must waste time. You are used to play video games, but you must to change. Last year, I should studied more. If I had studied, I will pass. You must to learn.
✅ 修正版： “You must study harder. You don’t have to waste time. You are used to playing video games every night, but you must change. Last year, I should have studied more, but I didn’t. If I had studied, I would have passed the exam. You must learn from my mistake.”
修正了 7 處：
- musts → must（沒三單）
- don’t must → don’t have to（don’t + must 不存在）
- play → playing（be used to + V-ing）
- must to → must（不加 to）
- should studied → should have studied（過去遺憾）
- will pass → would have passed（假設過去結果）
- must to learn → must learn（不加 to）
課前快問 解答
詳見前面解答區。
自我評分
| 分數（30 題） | 等級 | 建議 |
|---|---|---|
| 27-30 | 🏆 威威等級 | 助動詞精通！進入 21 倒裝句。 |
| 22-26 | 🥈 穩健等級 | 重點複習：should have、used to 三胞胎、must vs. have to 否定。 |
| 16-21 | 🥉 加油等級 | 把「modal + have + V-pp」表 + 「used to 三胞胎」背熟。 |
| 0-15 | 💪 再出發 | 從助動詞 4 大鐵律開始。 |
複習計畫
時間 內容 今天 全文 + 即時練習 + 章末測驗 第 3 天 默寫 modal + have + V-pp 表 + used to 三胞胎 第 7 天 寫 5 句遺憾句（should have / shouldn’t have） 第 14 天 找 1 段英文文章，圈所有助動詞並判斷用法 考試前 重看「6 大陷阱」
學習科學小知識：交錯練習 (Interleaved Practice)
不要一次只練 must、再一次只練 should——把它們混在一起練！研究 (Rohrer 2015) 顯示：交錯練習效果好 40%。
為什麼？考試題目是隨機出現的——你需要的不是「會」，而是「能辨別什麼時候用什麼」。每題逼你重新判斷——這個判斷動作本身就是學習。
應用：本講義的 30 題章末測驗就是「8 種助動詞混合」——多做幾遍，反射動作就建立了。