内容简介
“Must” 和 “have to” 都可以用来表示 “必须做……” 。然而，它们的否定形式 “mustn’t” 和 “don’t have to” 可能会让人感到困惑。它们之中，哪个是 “绝对不能做”？哪个是 “可做可不做”？“一分钟英语” 为你快速讲解它们的区别。
文字稿
Kee
Hi guys! This is Kee from BBC Learning English. Today, I’m going to tell you the differences between ‘mustn’t‘ and ‘don’t have to‘.
Now, ‘must’ and ‘have to’ are similar in meaning. They are both used to describe obligations. However, their negative forms are completely different in meaning.
We still use ‘mustn’t‘ to talk about obligations. For example: In the house, I mustn’t wear shoes. You know, to keep the house clean.
But ‘don’t have to‘ does not describe obligations, so the choice is yours! For example, if your teacher said: you don’t have to do your homework, well… then the choice is yours. You can say: Alright, I won’t!
用法小结
Mustn’t and don’t have to
1. Modal verbs
情态动词
Must, mustn’t, have to and don’t have to are modal verbs. This means they are always followed by a bare infintive verb. Unlike most modal verbs, have to and don’t have to change verb form when the subject pronoun changes. For example, becoming has to and doesn’t have to or had to and didn’t have to.
“Must、mustn’t、have to” 和 “don’t have to” 都是情态动词，后接动词原形。与多数情态动词不同，“have to” 和 “don’t have to” 的动词形态会随着句中主格代名词的变化而相应地变成 “has to、doesn’t have to、had to” 或 “didn’t have to”。
- I must go.
- We mustn’t go.
- You have to go.
- He doesn’t have to go.
2. Must and have to
Both must and have to refer to obligation. They explain what needs to be done.
“Must” 和 “have to” 两者都可以表 “义务”，说明必须要做的事情。
- You must stop smoking. It will kill you.
- You have to go to school. It’s the law.
3. Mustn’t
Mustn’t also refers to obligation, but in this case, it tells us what cannot be done.
“Mustn’t” 也可以用来表 “义务”，但用它来说明一件不能做的事情。
- You mustn’t talk to your mother like that.
- He mustn’t leave the house until I come home.
- We mustn’t eat any more chocolate.
4. Don’t have to
Don’t have to explains to us that there is no obligation to do something. As a result, we have free choice! You can choose to do this thing or not.
“Don’t have to” 用来说明不一定非要做某事。所以最终做与不做，可自行选择。
- You don’t have to go to school if you are sick.
- She doesn’t have to come to the party, if she doesn’t want to.
- I don’t have to know all the moves to win the game!