1. Mike, you__1__play with fire. You__1__ 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__2__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__3__

A. mustn't B. needn't C. can't D. may not

4. Jack's ill, so they__4__change their plans.

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

5. Harry has been reading all day —he__5__be tired.

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

答案：

1-5 BABCD

一、must的用法

1）表示主觀的義務和必要, 主要用于肯定句和疑問句, 意思為 “必須……，得……，要……”；由must引起的疑問句，肯定回答要用must或have to, 否定回答要用needn’t或don’t have to, 意思是“不必”；must的否定形式mustn’t表示禁止，意思是“不能，不許”。如：

We must find a good method to learn computer well.

document.write("<span id=ad_dst"+ad_dst+"></span>");ad_dst = ad_dst+1; 我們必須找一個學好電腦的方法。

—Must I finish the task right now?

我現在必須完成這個工作嗎？

—Yes, you must. / Yes, you have to. 是的。

(—No, you needn't. / No, you don't have to. 不，不必。)

You mustn't come here without permission. 未經允許，你不能來這兒。

2）表示肯定的猜測，常用于肯定句中，意思為 “一定是, 必然……”。

注意must表示推斷或猜測的幾種情況:

Your sister must be a doctor in this hospital. （現在的猜測）

你姐姐一定是這家醫院的醫生。

He must be reading newspapers in the reading room now.

（正在進行的猜測）

他此刻一定正在閱覽室讀報。

It must have rained last night, for the ground is wet. （過去的猜測）

昨晚一定下雨了，因為地面上是濕的。

二、have to / have got to 的用法

1）must表示一種主觀的需要，而have to 表示一種客觀的需要，意思是“不得不”。 如：

I have to attend an important meeting this afternoon.

今天下午我不得不參加一個重要的會議。

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

媽媽不在家，因此我不得不照看商店。

2）have to 的否定形式是don't have to, 相當于needn't。如：

They don't have to buy a computer at present.

他們目前沒有必要買電腦。

3）have to 與have got to 常可以互換。