情景导入
暑假你去游泳馆，会遇到这样三句话：I can swim.（我会游泳——能力。）You must wear a swimming cap.（你必须戴泳帽——规定。）We have to leave at 5 p.m.（我们不得不五点离开——闭馆了，客观所迫。）can、must、have to 都属于情态动词（或情态表达），它们自己不能单独作谓语，要和动词原形搭档，给句子加上"能力、义务、必要"等色彩。
核心词汇
| 词 | 核心含义 | 例句 |
|---|---|---|
| can / can't | 能、会；不能、不会 | I can play the piano. / He can't ride a bike. |
| must / mustn't | 必须；禁止 | You must finish it today. / You mustn't smoke here. |
| have to / don't have to | 不得不；不必 | I have to get up early. / You don't have to wait. |
句型与语法
共同规则：情态动词后必须接动词原形，不随人称变化（have to 除外）。
① can —— 能力与许可
- 能力：She can speak three languages. 许可：Can I use your pen? — Sure. 否定用 can't / cannot；疑问：Can 提前 → Can you dance? — Yes, I can. / No, I can't.
② must —— 主观上的"必须"
- 表示说话人主观认为必要，或规章制度：You must do your homework first. （你必须先写作业。）
- 疑问：Must I go now? — Yes, you must. / No, you needn't.（注意：否定回答不用 mustn't）
③ have to —— 客观上的"不得不"
- 表示客观条件迫使：It's raining, so I have to stay at home. 要随人称和时态变化：He has to work on Sundays. / I had to walk home yesterday.
- 否定和疑问要借助 do：He doesn't have to come. / Do you have to leave?
听说训练
班规大声说（两人一组，用 must / mustn't 说班级规则）：
- We must listen to the teacher carefully. （我们必须认真听老师讲课。）
- We mustn't eat in the classroom. （我们不许在教室里吃东西。）
- 能力小采访：Can you play chess? — Yes, I can. / No, I can't, but I want to learn.
辨析对比
① must vs have to
| must | have to | |
|---|---|---|
| 语气来源 | 主观（说话人认为必须） | 客观（环境、规定所迫） |
| 人称时态 | 不变化 | 随人称、时态变化（has to / had to） |
| 例句 | I must study hard.（自我要求） | I have to wear glasses.（近视了，没办法） |
② mustn't vs don't have to（最易混！）
- You mustn't park here. = 禁止在这里停车。（不许做）
- You don't have to park here. = 你不必在这里停车。（可做可不做）口诀：mustn't 是"禁止"，don't have to 是"不必"。
文化角
在英语国家的公共标志上，情态动词随处可见：Visitors must sign in at the front desk.（访客必须在前台登记。）/ You mustn't feed the animals.（禁止投喂动物。）而礼貌请求时，英语母语者更爱用 Could I...?（Can 的委婉形式）：Could I open the window?
易错点
- 情态动词后用了非原形：She can swims. ❌ → She can swim. ✅
- can 前多加 do：Do you can ride a bike? ❌ → Can you ride a bike? ✅
- mustn't 与 don't have to 混淆："不必"说成 mustn't ❌；"禁止"才用 mustn't ✅
- Must...? 的否定回答：No, you mustn't. ❌ → No, you needn't / you don't have to. ✅
中考真题
— Must I hand in the report today, Mr. Wang?
— No, you ______. You can give it to me tomorrow.
A. mustn't B. can't C. needn't D. shouldn't
✏️ 点击查看解答
答案：C
解析：Must I...?（我必须……吗？）的否定回答不能用 mustn't（mustn't 表示"禁止"），要用 needn't 或 don't have to，表示"不必"。后句 "You can give it to me tomorrow."（你可以明天交）正说明"今天不交也行"，即"不必"，选 C. needn't。A 项"禁止交"、B 项"不能交"、D 项"不应该交"，都与语境矛盾。
考点
- 情态动词是中考单选和完形填空的常客，七年级下打好基础至关重要；
- 中考命题点：① must 与 have to 的主客观之分 ② mustn't（禁止）与 don't have to（不必）辨析 ③ Must...? 的否定回答用 needn't。
诵读 Read Aloud
Part 1 · 对话：Can you...?（分角色朗读）
A: Can you play basketball, Mike?
B: Yes, I can. But I can't play it today. I have to look after my little brother.
A: I see. Must you stay at home all day?
B: No, I needn't. I can go out after four o'clock. But we must go home before dinner.
Part 2 · 短文：Rules in Our School（体会情态动词的语气）
There are many rules in our school. We must arrive on time, and we mustn't be late for class. In the library, we must keep quiet, and we mustn't bring food inside. I have to wear the school uniform from Monday to Friday, but I don't have to wear it on weekends. Some rules are strict, but I know they can help us. If everyone follows the rules, our school can be a better place.
诵读小贴士：朗读 Part 2 时，把 must / mustn't / have to / don't have to 圈出来，边读边判断语气——背熟这段，写"规则"话题作文时可以直接化用。