can的用法及练习

情态动词.can 的用法：

一、简介

1、结构：can + 动词原形，没有人称和数的变化。

2、否定形式：cannot/can’ t, cannot比缩略形式can’ t要正式。口语中一般用缩略形式。

例如：I can swim.

Daming can ride a bike. He can’t drive a car.

二、用法

1、表示能力（体力、知识、技能等），此时可用be able to代替。

例如：Mary can speak three languages. 玛丽会说三种语言。

= Mary is able to speak three languages.

注意：（1）can只有一般现在时和一般过去式；而be able to则有更多的时态。

例如：I’ll not be able to come this afternoon. 今天下午我将会来。

（2）当表示“经过努力才得以做成功某事”时应用be able to，不能用can。

例如：He was able to go to the party yesterday evening in spite of the heavy rain. 尽管很大雨，他昨天能来参加聚会。

2、表示请求和允许。

例如：---Can I go now?

--- Yes, you can. / No, you cannot/can’t.

此时可与may互换。在疑问句中还可用could, might（不可用于肯定句、否定句或答语）代替，不是过去式，只是语气更委婉。

例如：--- Could I come to see you tomorrow?

--- Yes, you can. ( No, I’m afrai d not. )

3、表示可能性猜测。

例如：The man over there can′t be my uncle. My uncle has gone to Beijing.

那个人不可能是我的叔叔。我的叔叔去北京了。

三、练习题

( )1．---Susan’s parents have bought a large house with a swimming pool.

---It ______ be very expensive.

A．must B．can C．mustn’t D、can’t

( )2．The notebook______ belong to Sarah．Her name is on the cover．

A．might B．can’t C．must D．mustn’t

( ) May I put my bike here?

--- No，you______．You should put it over there．

A．couldn’t B．needn’t C．mustn’t D．won’t

( )4．Boys，you______ be sitting in this room．It is for your teachers only． A．shouldn’t B．don’t have to C．won’t D．needn’t

( )5．---Whose pizza is this?

---I think it______ be mine．I’m the only one who ordered a pizza．

A．must B．could C．might D．can’t

( ) 6. My brother can’t sing but he ______ play the piano.

A. can’t

B. doesn’t

C. can

D. don’t

( )7. You look tired. You ______ to have a good rest.

A. must

B. may

C. should

D. need

( ) Why do you think the man is running ?

---He ______ be ______ for exercise because he is wearing a suit .

A. must , running

B. can’t ; run

C. can’t ; running

D. could ; running

( )9. ---Mum , I’ve been studying English since 8 o’clock. ______ I go out and play with Tom for a while?

---No, I’m afraid not. Besides, it’s raining outside now.

A. Can’t

B. Wouldn’t

C. May not

D. Won’t