说出规则
能说出什么是必须做的，什么是禁止的，什么是不必做的。
标注的核心时长。核心模块中有两项未标注时长，因此实际课时比总和更长。
语法
5 分钟must 和 have to 都表示“必须”，但“必须”的来源不同。
| 来自哪里 | 例子 | |
|---|---|---|
| must | 来自说话人自己：我这样决定，我认为这很重要 | I must call my mother today. |
| have to | 来自外部：规定、法律、客观情况 | I have to wear a uniform at work. |
口语里这个区别常常被淡化，have to 用得更多：它在哪儿都合适。但有一个区别绝对不能忽视：
mustn't 和 don't have to 不是一回事，而是意思相反。
| You mustn't smoke here. | 这里不许抽烟。禁止。 |
| You don't have to come tomorrow. | 明天不必来。可以不做。 |
形式。 must 是情态动词：不加 -s，不用 do，后面接动词原形。 have to 是普通动词：he has to，Do you have to…?，I don't have to。
| He must go. / He has to go. | |
| Do you have to work on Sunday? | |
| I don't have to work. |
must 没有过去式——说过去要用 had to：I had to work yesterday。
中文母语者的常见错误
已针对你的语言编写用 mustn't 表示“不必”。
✗ You mustn't come tomorrow（想说“可以不来”）→ ✓ You don't have to come tomorrow。must 记作“必须”，而“必须”的否定是“不必”，于是 mustn't 很容易被当成“不必”。其实它的意思是“不许”。这个错误把意思说反了，所以比别的错误代价更大。
must 后面加 to。
✗ I must to go
✓ I must go
。“必须走”中间什么都不加，英语也一样；to 是从 have to 带过来的。
说过去的事还用 must。
✗ Yesterday I must work late，✗ I musted work → ✓ Yesterday I had to work late。汉语“昨天我必须加班”里的“必须”不变，过去靠“昨天”表示； must 没有过去式，要换成 had to。
第三人称用 have to。
✗ She have to wear a uniform
✓ She has to wear a uniform
。汉语动词不随主语变化，而 have to 是普通动词，在 he、she 后面要变成 has to。
发音
3 分钟mustn't 中间的 t 不发音： /ˈmʌsnt/。/s/ 直接连着 /n/，中间不要加元音。
have to 在语流中读 /ˈhæftə/，是 /f/ 音，不是 /v/。has to 读 /ˈhæstə/。这不是说得马虎，而是标准读法；听到 /aɪ ˈhæftə ɡəʊ/，就是 I have to go。
课文
3 分钟At my work we have to wear a uniform, and we have to be there at nine. You mustn't use your phone in the office — it's a rule. On Friday we don't have to stay until six. We can go home at four. Yesterday I had to work late because my colleague was ill.
练习
8–10 分钟1. 填空。
- You smoke here — it's forbidden
- You come tomorrow — it's Sunday
- Children play with matches
显示答案
2. 填空。
- I call my mother today — I really want to
- She wear a uniform at work
- Yesterday I work late
显示答案
3. 改错。
- I must to go.
- I musted work yesterday.
- You mustn't come tomorrow.（意思是“不必来”）
显示答案
4. 配对。
- You mustn't go.
- You don't have to go.
显示答案
小结
本课已学：must 和 have to，禁止和“不必”的区别，说过去用 had to。下一课——第11课：建议和看法。
核心内容结束
完成练习后即视为课程结束。此后的内容均为可选。
可选
词卡词汇
12 词- rule /ruːl/ 规则，规定
- uniform /ˈjuːnɪfɔːm/ 制服
- forbidden /fəˈbɪdn/ 被禁止的
- allowed /əˈlaʊd/ 被允许的
- smoke /sməʊk/ 抽烟，吸烟
- colleague /ˈkɒliːɡ/ 同事
- office /ˈɒfɪs/ 办公室
- late /leɪt/ 晚的，迟
- early /ˈɜːli/ 早的，早
- careful /ˈkeəfl/ 小心的，谨慎的
- important /ɪmˈpɔːtnt/ 重要的
- necessary /ˈnesəsəri/ 必要的，必需的
写作
写四个句子，讲讲你工作或学习的地方有哪些规定：什么是必须做的，什么是禁止的，什么是不必做的。
范例： At my work we have to wear a uniform. We have to be there at nine. You mustn't use your phone in the office. On Friday we don't have to stay until six.
检查清单：禁止用的是 mustn't，“不必”用的是 don't have to 吗？must 后面没有 to 吧？