初三(英语): 情态动词全攻略——can, must, should, may

📅 2026-05-30

初三英语：情态动词全攻略——can, must, should, may

一、知识点精讲

（一）什么是情态动词？

情态动词（Modal Verbs） 是用来表示说话人的语气或态度的助动词。它们本身有一定含义，但不能单独作谓语，必须和行为动词（原形）一起构成谓语。

情态动词 含义 否定形式 例句
can 能够；可以 cannot / can't I can swim.
must 必须 must not / mustn't You must finish homework.
should 应该 should not / shouldn't We should help others.
may 可以；可能 may not May I come in?

（二）四大情态动词用法对比

1. can —— 能力、许可、可能性

用法 说明 示例
表示能力 某人能做某事 She can speak three languages.
表示许可 口语中表示"可以" Can I use your pen?
表示可能性 推测（常用于否定/疑问） It can't be true.

2. must —— 必须（主观）、禁止、必然

用法 说明 示例
表示义务 出于主观认为"必须"做 You must wear a mask.
表示禁止（否定） mustn't = 绝对不可以 You mustn't smoke here.
表示推测 对现在情况的肯定推测 He must be at home.

⚠️ 易混点： must 的否定是 needn't（不必）或 don't have to，而不是 mustn't！mustn't 是"禁止"。

3. should —— 应该、建议

用法 说明 示例
提建议 认为某件事应该做 You should see a doctor.
表责任 道德或义务上的应该 We should protect the environment.
表推测 预期会发生的事 The train should arrive soon.

4. may —— 可能、允许

用法 说明 示例
表允许 正式场合的"可以" May I leave now?
表推测 不确定的可能性（<50%） It may rain tomorrow.
表祝愿 固定句型 May you succeed!

（三）情态动词核心结构

肯定句：主语 + 情态动词 + 动词原形 + 其他.
否定句：主语 + 情态动词 + not + 动词原形 + 其他.
疑问句：情态动词 + 主语 + 动词原形 + 其他?

常见易错点对比表

场景 正确表达 ❌ 错误表达
过去能力 could swim can swam
将来能力 will be able to can will
否定推测 can't be mustn't be
过去必须 had to musted
建议否定 shouldn't go should not to go

二、经典例题

💡 例题1：单项选择——语境辨析 **(1)** — Must I finish the report today? — No, you ______. You can hand it in tomorrow. A. mustn't B. needn't C. can't D. shouldn't **解析：** 回答以 must 开头的疑问句，否定用 needn't（不必）或 don't have to。mustn't 表示"禁止"。 **答案：** B **(2)** Listen! Someone is singing in the next room. It ______ be Lucy. She loves singing. A. must B. can't C. may D. should **解析：** 听到房间有人唱歌，且 Lucy 喜欢唱歌，这是很有把握的推测，用 must（肯定推测）。 **答案：** A **(3)** You ______ cross the street when the red light is on. It's dangerous! A. needn't B. mustn't C. may not D. shouldn't **解析：** 红灯时过马路是禁止的，语气最强的是 mustn't（绝对不许）。 **答案：** B
💡 例题2：句型转换——情态动词改写 将下列句子按要求改写： 1. You can play football here.（改为否定句） → You cannot / can't play football here. 2. She should go to the hospital.（改为一般疑问句） → Should she go to the hospital? 肯定回答：Yes, she should. 否定回答：No, she shouldn't. 3. We must finish the work before 6 pm.（改为否定句，表示"不必"） → We don't have to / needn't finish the work before 6 pm. （注意：mustn't 表示禁止，这里不适用）
💡 例题3：完形填空——情态动词综合运用 阅读短文，选择最恰当的情态动词： > Tom is a good student. He (1)______ get up early every morning to catch the school bus. He thinks students (2)______ be on time. But today he woke up late. "I (3)______ be late for school!" he said to himself. "I (4)______ take a taxi, I guess." He told his mom, "I (5)______ miss the first class." (1) A. must B. may C. can D. should (2) A. must B. should C. can D. may (3) A. mustn't B. may not C. can't D. needn't (4) A. should B. can C. must D. need (5) A. mustn't B. shouldn't C. needn't D. can't **参考答案：** (1)A (2)B (3)A (4)A (5)D **解析：** - (1) Tom 每天必须早起，是客观需要 → must - (2) 应该准时是建议 → should - (3) 绝对不能迟到 → mustn't - (4) 应该打车，是自己的判断 → should - (5) 不能错过第一节课 → can't（能力上的不可能）

三、趣味练习

🎯 闯关游戏：情态动词大闯关 ### 第一关：火眼金睛——找出错误 以下各句各有一处错误，请找出来并改正： 1. You mustn't worry about it. Everything will be fine.（__？__） 2. She cans play the piano very well. 3. May I to open the window? 4. He must studies hard to pass the exam.
✅ 查看答案 1. mustn't → needn't / don't have to（不必担心，不是禁止） 2. cans → can（情态动词后加动词原形，不需要三单） 3. to open → open（情态动词后跟动词原形） 4. studies → study（情态动词后跟动词原形）
### 第二关：填空大挑战 根据语境填入合适的情态动词： 1. You ______ brush your teeth before going to bed.（建议） 2. ______ I use your phone? I need to call my mom.（请求许可） 3. That ______ be Jack. He is in Beijing now.（否定推测） 4. You ______ park here. It's a no-parking zone.（禁止） 5. It's raining outside. You ______ take an umbrella.（建议）
✅ 查看答案 1. should 2. May / Can 3. can't 4. mustn't 5. should
### 第三关：情景对话 根据情景，补全对话： A: Mom, (1)______ I go out and play basketball? B: (2)______ you finish your homework first? A: Yes, I have only one problem left. B: OK, you (3)______ go after finishing it. A: Thanks, Mom. I (4)______ be back before dinner. B: You (5)______ be late! Dinner is at 6 sharp.
✅ 查看答案 1. Can / May 2. Did（一般疑问句），或 Have 3. can / may 4. will 5. mustn't（不许迟到！）

四、课后作业

基础题（★★☆☆☆）

  1. 用括号内情态动词的适当形式填空：
  2. (1) You ______ (should / not) stay up too late.
  3. (2) She ______ (can / not) speak Japanese.
  4. (3) ______ (may) I ask you a question?

  5. (4) We ______ (must) clean the classroom every day.

  6. 将下列句子改为否定句：

  7. (1) You can leave now.
  8. (2) He should tell the truth.
  9. (3) They must arrive on time.

提高题（★★★☆☆）

  1. 汉译英：
  2. (1) 你必须按时完成作业。
  3. (2) 我可以借你的自行车吗？

  4. (3) 你不应该在课堂上玩手机。

  5. 选择最佳答案：

  6. (1) You ______ come if you are busy. I can do it alone. A. mustn't B. needn't C. can't D. shouldn't
  7. (2) — Is Tom in the library? — I'm not sure. He ______ be there. A. must B. can C. may D. should

挑战题（★★★★☆）

  1. 短文改错：下面短文中有5处情态动词用法错误，请找出来并改正：

"Students should works hard at school," said our teacher. "You can to ask questions anytime. But you mustn't copy others' homework. If you have problems, you cans ask me for help. You mustn't to worry about making mistakes — nobody can be perfect. However, you shouldn't makes the same mistake twice."

  1. 写作：用至少4个不同的情态动词（can, must, should, may），写一段80词左右的短文，谈论你认为一个好学生应该具备的品质。