初一英语：情态动词can,must,may的用法

4. 表示说话人的猜测、怀疑、不肯定等，主要用于否定句、疑问句、感叹句中，带哟感情色彩。

How can yo be so rude!

Can he be back?

5. could可以作为can的过去式，也可以在提出请求时表示委婉。

He could save the little boy.

Could you help me?

三、may, might

1. 表示“许可、准许”，此时与can同义，可以互换使用

You may/can go to the cinema this evening.

☆注意：表许可时其答语可以用“Yes,you may.”但是由于用may做肯定回答语气显得生硬、严肃，因此一般用Yes, please. /Certainly. / Of course.这些回答显得热情、客气。

拒绝对方时，其答语可以用No, you mustn’t. / No, you can’t. / Sorry, you can’t. / No, please don’t等

--May I come in? --Yes, please

--May I use your ruler? --Certainly. Here you are.

2. 表示可能性时，常用在肯定句中，意为“可能、也许”

He may be very busy now.

He said that she might not be at work today.

3. can和may都可以表示推测。Can通常用在否定句和疑问句中，may通常用在肯定句和否定句中。虽然两者都可以用于否定句，但是程度不同，can’t的语气比may not更强。

It can’t be true.

It may not be true.

4. 表示希望、祈求、祝愿，常可以译为“祝愿”

May you have a good time.

May you be happy.

5. might可以作为may的过去式，也可以在提出请求时表委婉；在表示可能性时，might的可能性比may 更小

☆注意：can和may的区别

1. can和may都可以表示“许可”，在征求对方意见时用may比较多May I go now?

2. 在询问客观上是否可以时，用can Can we take the books out?

3. 在两者都可以用时，may更客气一些

4. 在陈述句中用can比较多You can sit here.

5. can还可以表示能力，may无此用法

6. 在否定句中一般不用may not，常用can’t表示不可能

He can’t be at home tonight.

四、must

1. 表示“必须、一定要”，多强调说话人的主观看法（表示客观需要时，常用_____________）

否定式mustn’t表示“一定不要，禁止”

You must see the doctor.

Must you go soon?

对于must开头的一般疑问句，如果要做否定回答，可以用needn’t, don’t have to，不能用mustn’t --Must I come over tonight? --No, you needn’t

2. 表示推测，意为“准是，一定是”，但是通常只用于肯定句，在否定句、疑问句中通常用can’t

It must be true.

Can it be true? It can’t be true

Step 3：Practice

一、用can，may，must的适当形式填空

1. __________ I ask you a question?

2. Attending a ball __________ be exciting

3. Michael __________ be a policeman, for he is mush too short.

4. –Are you coming to Jeff’s party? --I’m not sure. I __________ go to the concert instead.

5. He never takes a taxi. He __________ be very poor.

6. I thought you __________ like something to read, so I brought you some books.

7. Look! I __________ stand on my hands.

8. He __________ have been to Shanghai.

9. The play is not interesting. I really __________ go now.

10. She __________ like this place.

二、根据汉语提示给出下列句子的回答

1. –Must we hand in our exercise books today?

______________________________.(不，没有必要)

2. Can I call you by your first name?

______________________________(是的，可以)

3. Could I come here again tomorrow?

______________________________(是的，你可以来)

4. Must we send in our pla this week?

______________________________(是的，必须交)

5. May I use you pen?

______________________________(可以，给你)

三、选择

1. Helen __________ go on the trip with us, but she isn’t quite sure yet.

A shall

B must

C may

D can

2. Johnny, you __________ play with the knife, you __________ hurt yourself.

A won’t ,can’t

B mustn’t, may

C shouldn’t , must

D can’t, shouldn’t

3. A computer __________ think for itself; it must be told what to do.

A can’t

B couldn’t

C may not

D might not

4. –Could I borrow your dictionary? --Yes, of course you __________.

A must

B might

C can

D could

5. How __________ you say that you really understand the whole story if you have covered only a part of the article?

A can

B must

C need

D may

6. Oh, dear! What on earth __________ this mean?

A could

B can

C may

D might

7. –Must I finish my homework today? --No, you __________.

A can’t

B needn’t

C mustn’t

D may not

8. --__________ I speak to Mary? --Speaking.

A Must

B Need

C May

D Shall

9. This match problem is too hard. Nobody __________ do it.

A may not

B may

C can’t

D can

10. –Can you speak Japanese? --No, I __________.

A can’t

B mustn’t

C may not

D needn’t