I have to attend an important meeting this afternoon. 今天下午我不得不参加一个重要的会议。

Mother is out， so I have to look after the shop.

妈妈不在家，因此我不得不照看商店。

2)have to 的否定形式是don‘t have to， 相当于needn’t.如： They don‘t have to buy a computer at present.

他们目前没有必要买电脑。

3)have to 与have got to 常可以互换。

三、巩固练习：

从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。

1. Mike， you ______ play with fire. You______ burn yourself.

A. won‘t; can’t B. mustn‘t; may

C. don‘t have to; must D. have got to; shouldn’t

2. You ______ see the doctor， Joe. You don‘t look very well.

A. must B. shall C. may D. can

3. —Must I clean the window now?

—No， you ______.

A. mustn‘t B. needn’t C. can‘t D. may not

4. Jack‘s ill， so they ______ change their plans.

A. must B. should C. have got to D. ought to

5. Harry has been reading all day —he ______ be tired.

A. should B. has got to C. has to D. must