情景导入
开学第一天，班主任在班会上宣布班规。如果用英语开班会，她会怎么说？
- Don't be late for class. （上课不要迟到。）
- You must wear the school uniform. （你们必须穿校服。）
俗话说 No rules, no order（没有规矩，不成方圆）。本单元我们就来学习"制定规则、谈论规则"的两大法宝：祈使句和情态动词。
核心词汇
规则高频词：
| 单词/短语 | 意思 | 例句 |
|---|---|---|
| rule | 规则 | follow the rules 遵守规则 |
| be late for | 迟到 | Don't be late for school. |
| hallway | 走廊 | Don't run in the hallways. |
| uniform | 校服 | wear the school uniform |
| dining hall | 餐厅 | eat in the dining hall |
| quiet | 安静的 | keep quiet in the library |
情态动词一览：must（必须）、can（可以）、can't（不可以）、have to（不得不）、don't have to（不必）
句型与语法
一、祈使句：直接下命令
祈使句以动词原形开头，省略主语 you：
- 肯定：Be quiet, please. / Listen to the teacher.
- 否定：Don't run in the hallways. / Don't be late. （be 动词开头的否定也用 Don't）
二、must / can't：谈论规则
- We must be on time. （我们必须准时。——强调必要性）
- Students can't fight. （学生不许打架。——表示禁止）
三、have to：客观上的"不得不"
- I have to get up at six because my home is far from school. （客观条件所迫）
- 三单形式：He has to wear a uniform.
- 否定：don't have to = 不必（不是"禁止"）：You don't have to come early on Sunday.
听说训练
规则问答（两人一组，谈论校规）：
- What are the rules at your school? — We must wear uniforms on weekdays.
- Can we eat in the classroom? — No, we can't. We have to eat in the dining hall.
辨析对比
① must vs have to
| must | have to | |
|---|---|---|
| 含义 | 主观认为必须 | 客观条件不得不 |
| 人称变化 | 无变化 | 三单用 has to |
例：I must finish my homework first.（自己觉得必须）/ We have to stay at home because of the rain.（客观原因）
② mustn't vs don't have to
- You mustn't smoke here. = 禁止，绝对不行。
- You don't have to wear a uniform on weekends. = 不必，可做可不做。考试最爱在这里挖坑。
文化角
英美中学也有校规：很多英国学校要求穿校服（school uniform），美国学校则普遍允许便装，但对迟到（tardiness）管理很严。公共场合的提示语也常用祈使句：Keep off the grass.（勿踏草坪）/ No parking.（禁止停车）——No + 名词/动名词也是表达"禁止"的常见方式。
易错点
- 祈使句否定：Not run in the hallways. ❌ → Don't run in the hallways. ✅
- 三单漏变：He have to wear a uniform. ❌ → He has to wear a uniform. ✅
- mustn't 与 don't have to 混淆："不必"要用 don't have to，用 mustn't 就变成"禁止"了。
中考真题
— Mom, can I play computer games this evening?
— No. You ______ finish your homework first. That's the rule of our family.
A. can B. must C. may D. could
✏️ 点击查看解答
答案：B
解析：妈妈先说了 No（拒绝），又提到 That's the rule of our family（这是家规），语气强硬，表示"必须先完成作业"，选 must。A、C、D 三项都表示许可或可能，与"家规要求"的强制语气不符。
考点
- 情态动词辨析（must / can / have to / mustn't / don't have to）是单选高频考点；
- 祈使句的否定形式 Don't + 动词原形，常在补全对话和标志语理解题中出现。
诵读 Read Aloud
There are many rules at my school in Hangzhou. We have to be at school before 7:50 in the morning, so I must get up early. We must wear the school uniform on weekdays and keep our classroom clean. In class, we can't eat or use phones, and we must listen to the teacher carefully. In the hallways, we can't run or shout. We also have to be quiet in the library. Some rules are strict, but I know they are good for us. No rules, no order!
诵读小贴士：注意 must 后动词读原形，语气坚定；圈出文中所有 have to / must / can't，体会"客观不得不、主观必须、禁止"三种语气的不同。