Appearance
Unit 31 — have to and must
1. have to 的核心含义
have to do something = it is necessary to do it / I am obliged to do it
也就是：
have to = 必须 / 不得不 / 有必要做某事
核心不是“我想做”，而是：
客观上有这个必要，或者有某种外部要求。
A. have to
2. 基本结构
have to + 动词原形
例如：
You have to turn left here.
你在这里必须左转。
因为：
You can’t turn right here.
这里不能右转。
所以：
have to = 没有别的现实选择
3. Example — wear glasses
I have to wear glasses for reading.
我看书时必须戴眼镜。
这里表达：
对我来说，这是实际需要。
4. 第三人称：has to
主语是：
he / she / it
时：
have to → has to
例如：
Robert can’t come out with us this evening. He has to work late.
Robert 今晚不能和我们出去。
他必须加班到很晚。
5. 过去：had to
过去需要做某事：
had to + 动词原形
例如：
Last week Tina broke her arm and had to go to hospital.
上周 Tina 摔断了胳膊，不得不去医院。
注意：
过去不用 musted
也通常不用 must 来表达过去的“必须”。
而是：
had to
6. 现在完成时：have had to
例如：
I haven’t had to go to the doctor for ages.
我已经很久都没有需要去看医生了。
结构：
have/has + had to + 动词原形
所以：
| 时间 | 结构 |
|---|---|
| 现在 | have to |
| 第三人称现在 | has to |
| 过去 | had to |
| 现在完成 | have/has had to |
7. have to 像普通动词一样变化
这是非常重要的一点。
have to 在疑问句和否定句中，需要：
- do
- does
- did
8. 疑问句：do I have to...?
What do I have to do to get a new driving licence?
我要做什么才能拿到新的驾照？
正确：
✅ What do I have to do?
不是：
❌ What have I to do?
在现代英语中，通常使用：
do + have to
9. 否定句：doesn’t have to
Karen doesn’t have to work Saturdays.
Karen 星期六不用工作。
注意：
doesn’t have to = 没有必要
不是：
禁止
这个区别非常重要。
10. 过去疑问：Did you have to...?
Did you have to wait a long time for a bus?
你等公交车等了很久吗？
回答：
No, only ten minutes.
没有，只等了十分钟。
结构：
Did + 主语 + have to + 动词原形?
不是：
❌ Did you had to...?
11. have to 的基本变化
| 类型 | Example |
|---|---|
| 肯定 | I have to go. |
| 第三人称 | She has to go. |
| 否定 | I don’t have to go. |
| 第三人称否定 | She doesn’t have to go. |
| 疑问 | Do you have to go? |
| 过去 | I had to go. |
| 过去疑问 | Did you have to go? |
12. 未来：will have to
have to 可以进入未来结构：
will have to + 动词原形
例如：
They can’t repair my computer, so I’ll have to buy a new one.
他们修不好我的电脑，所以我得买一台新的。
13. be going to have to
也可以说：
be going to have to + 动词原形
例如：
I’m going to have to buy a new computer.
我恐怕得买一台新电脑了。
14. might / may have to
还可以和 may / might 连用：
might have to + 动词原形
may have to + 动词原形
例如：
We might have to change our plans.
我们可能得改变计划。
或者：
We may have to change our plans.
意思是：
It’s possible that we will have to change them.
也就是：
未来有可能出现“不得不做”的情况。
15. have to 的灵活性
have to 最大的特点之一：
可以进入各种时态和情态结构。
例如：
| 结构 | Example |
|---|---|
| have to | I have to go. |
| has to | She has to go. |
| had to | I had to go. |
| have had to | I have had to go. |
| will have to | I will have to go. |
| might have to | I might have to go. |
| may have to | I may have to go. |
| going to have to | I’m going to have to go. |
这点和 must 不一样。
B. must vs have to
16. must 和 have to 很相似
很多情况下，两者都可以：
It’s later than I thought. I must go.
或者：
I have to go.
意思都可以理解成：
我得走了。
17. 说话者自己的判断：must / have to 都可以
如果是在表达：
说话者自己认为某件事有必要
或者：
说话者给别人建议
那么：
must 和 have to 都可以
18. Example — phone Sue
I haven’t spoken to Sue for ages. I must phone her.
或者：
I have to phone her.
意思：
我很久没和 Sue 联系了，我得给她打电话。
这里的“必须”来自：
说话者自己的判断
也就是：
“我觉得这件事有必要。”
19. Example — meet Mark
Mark is a really nice person. You must meet him.
或者：
You have to meet him.
意思：
Mark 人特别好，你一定得认识一下他。
这里：
must / have to
带有推荐意味。
即：
I recommend this.
20. must 的主观感觉
可以把 must 理解成：
“在我看来，这件事很有必要。”
例如：
You must try this restaurant.
你一定得试试这家餐厅。
这里不是法律规定。
而是：
说话者强烈推荐。
21. have to 更常用于客观义务
图片中特别强调：
We use have to (not usually must) to say what someone is obliged to do.
这里表达的是：
客观事实 / 外部规则 / 环境要求
而不是说话者自己的意见。
22. Example — work from 8:30 to 5:30
I have to work from 8.30 to 5.30 every day.
我每天必须从 8:30 工作到 5:30。
这里：
a fact, not an opinion
也就是说：
这是工作安排，不是我自己的建议。
23. Example — Jane has to travel
Jane has to travel a lot for her work.
Jane 因为工作不得不经常出差。
这里的必要性来自：
她的工作
不是说话者要求她。
24. must vs have to：主观 vs 客观
可以先这样理解：
| must | have to |
|---|---|
| 说话者认为有必要 | 外部条件使其有必要 |
| speaker’s opinion | external obligation |
| 主观要求 | 客观要求 |
| I must phone Sue. | I have to work until 5:30. |
不过这个区别不是绝对的。
很多情况下：
must / have to 都能用。
只是语气重点有所不同。
25. 一个直观的思维模型
must
必要性来源：
SPEAKER
也就是：
SPEAKER
↓
“必须做”
↓
MUST
例如：
You must meet Mark.
我认为：
你真的应该见见他。
have to
必要性来源：
OUTSIDE
例如：
RULE / JOB / SITUATION
↓
necessity
↓
HAVE TO
例如：
I have to work until 5:30.
因为：
工作制度如此。
26. 书面规则和说明中常用 must
虽然客观义务经常用 have to，
但在：
written rules and instructions
书面规定、规章、说明中，经常使用：
must
27. Example — applications
Applications for the job must be received by 18 May.
这份工作的申请必须在 5 月 18 日之前收到。
这里是：
正式规定。
28. Example — seat belts
Seat belts must be worn.
必须系安全带。
这里是：
正式规则 / 指示。
注意结构：
must be + 过去分词
这是被动语态：
must be worn
= 必须被佩戴。
29. 过去必须用 had to
图片特别强调：
We use had to (not must) to talk about the past.
例如：
I went to the meeting yesterday, but I had to leave early.
我昨天参加了会议，但是不得不提前离开。
不是：
❌ I must leave early.
因为这里说的是：
过去发生的必要行为。
所以：
had to
30. must 没有普通的过去式
这是必须记住的。
| 时间 | 常用形式 |
|---|---|
| 现在必要 | must / have to |
| 过去必要 | had to |
| 未来必要 | will have to |
| 可能需要 | may/might have to |
| 现在完成 | have had to |
所以：
have to 是更完整、更灵活的系统。
31. must vs have to 的结构差异
must
must + 动词原形
例如：
I must go.
注意：
- 不加 to
- 不加 s
- 不用 do/does
例如：
She must go.
不是：
❌ She musts go.
have to
have/has/had to + 动词原形
例如：
I have to go.
She has to go.
We had to go.
32. must 的疑问和否定
must 是情态动词。
所以疑问直接提前：
Must I go?
否定：
must not / mustn’t
例如：
You mustn’t smoke here.
这里禁止吸烟。
这一点和：
don’t have to
完全不同。
33. mustn’t vs don’t have to
这是非常重要的区别。
mustn’t
禁止 / 绝对不能
例如：
You mustn’t park here.
你绝对不能在这里停车。
意思：
不允许。
don’t have to
没有必要 / 可以不做
例如：
You don’t have to come tomorrow.
你明天不用来。
意思：
来也可以，不来也可以。
34. mustn’t vs don’t have to
| mustn’t | don’t have to |
|---|---|
| 禁止 | 没有必要 |
| must not do | no need to do |
| 不能做 | 可以不做 |
| ❌ 不允许 | ✅ 可做可不做 |
例如：
You mustn’t leave now.
你现在不能走。
vs
You don’t have to leave now.
你现在不用走。
完全不同。
35. 图片中的全部例句整理
have to
| Example | 中文 |
|---|---|
| You have to turn left. | 你必须左转。 |
| I have to wear glasses. | 我必须戴眼镜。 |
| He has to work late. | 他必须加班。 |
| Tina had to go to hospital. | Tina 不得不去医院。 |
| I haven’t had to go to the doctor. | 我一直没需要去看医生。 |
疑问和否定
| Example | 中文 |
|---|---|
| What do I have to do? | 我必须做什么？ |
| Karen doesn’t have to work Saturdays. | Karen 星期六不用工作。 |
| Did you have to wait long? | 你当时必须等很久吗？ |
未来 / 可能
| Example | 中文 |
|---|---|
| I’ll have to buy a new computer. | 我将不得不买新电脑。 |
| I’m going to have to buy one. | 我恐怕得买一台。 |
| We might have to change our plans. | 我们可能得改计划。 |
| We may have to change our plans. | 我们可能得改计划。 |
must / have to
| Example | 中文 |
|---|---|
| I must go. | 我得走了。 |
| I have to go. | 我得走了。 |
| I must phone Sue. | 我必须给 Sue 打电话。 |
| I have to phone Sue. | 我得给 Sue 打电话。 |
| You must meet Mark. | 你一定得见见 Mark。 |
| You have to meet Mark. | 你真的应该见见 Mark。 |
客观要求
| Example | 中文 |
|---|---|
| I have to work from 8.30 to 5.30. | 我必须按这个时间工作。 |
| Jane has to travel a lot. | Jane 因工作必须经常出差。 |
正式规则
| Example | 中文 |
|---|---|
| Applications must be received by 18 May. | 申请必须在 5 月 18 日前收到。 |
| Seat belts must be worn. | 必须系安全带。 |
过去
I went to the meeting yesterday, but I had to leave early.
我昨天参加了会议，但是不得不提前离开。
36. 最重要的时间变化表
| 时间 / 情况 | 结构 | Example |
|---|---|---|
| 现在 | have to | I have to go. |
| 现在第三人称 | has to | She has to go. |
| 过去 | had to | I had to go. |
| 现在完成 | have had to | I have had to work late. |
| 未来 | will have to | I’ll have to go. |
| 未来计划 | going to have to | I’m going to have to go. |
| 可能 | might have to | I might have to go. |
| 可能 | may have to | I may have to go. |
37. must 和 have to 快速对比
| 判断点 | must | have to |
|---|---|---|
| 基本意思 | 必须 | 必须 / 不得不 |
| 说话者自己的判断 | ✅ 常见 | ✅ 可以 |
| 外部规定/情况 | 可以 | ✅ 更常见 |
| 正式书面规定 | ✅ 常见 | 可以 |
| 过去 | ❌ 一般不用 | had to |
| 未来 | ❌ 不能直接变 | will have to |
| may/might 后 | ❌ | may/might have to |
| 现在完成时 | ❌ | have had to |
38. 最实用的判断方法
先问：
这个“必须”是从哪里来的？
来自我的判断 / 强烈建议
可以用：
must
例如：
I must phone her.
我觉得：
这件事真的该做。
来自工作、规则、环境等外部因素
更常用：
have to
例如：
I have to work tomorrow.
不是我自己想这么安排。
而是：
工作要求如此。
39. 然后再看时间
如果是：
现在
have to / must
过去
had to
未来
will have to
可能
might/may have to
所以：
时间复杂以后，基本就转向 have to 系统。
40. 母语思维
must
可以理解成：
“在我看来，这件事非做不可。”
例如：
You must see this movie.
你一定得看看这部电影。
不是法律要求。
而是：
我非常推荐。
have to
更像：
“现实情况逼着我这么做。”
例如：
I have to get up at 6 tomorrow.
我明天必须 6 点起床。
可能原因：
- 要上班
- 要赶飞机
- 有预约
这种必要性来自：
外部现实。
41. 最终思维模型
MUST
SPEAKER'S VIEW
│
▼
NECESSARY
│
▼
MUST
核心：
我认为有必要。
HAVE TO
RULE / JOB / SITUATION
│
▼
NECESSARY
│
▼
HAVE TO
核心：
现实要求我做。
42. 最重要的三个区别
must vs have to
must → 主观必要性更明显
have to → 客观必要性更明显
must vs had to
must → 现在
had to → 过去
mustn’t vs don’t have to
mustn’t → 禁止做
don’t have to → 没必要做
一句话记忆
must
我认为：这件事必须做。
have to
现实要求：这件事不得不做。
had to
过去不得不做。
will have to
未来将不得不做。
might/may have to
可能不得不做。
最核心：
MUST = speaker sees it as necessary
HAVE TO = circumstances make it necessary