情态动词1.(can ,may,will,shall)

情态动词

1.can / could

a.表示能力

He can speak a little

Japanese in addition to

English.

Man cannot live without air．

Can you finish this work tonight?

b.表示许可

You can(not) have the

book.

Can I use your

phone?

could也可表示请求，语气更委婉，主要用于疑问句，不可用于肯定句，答语应用can

(即：could不能用于现在时态的简略答语中)，如：

--Could l come to see you tomorrow morning7

--Yes，you can.(否定答语可用No，I'm afraid not．) Could you please …? Could I use your

dictionary? --- Yes, you can.

c. 有时候会

He is a bad-tempered fellow, but sometimes he can be charming.

They can be very valuable.

d. 在否定句和疑问句中表示猜测(can’t不可能) Someone is knocking. Who can it be?

It can’t be Mr. Li. Because he is away on business.不

可能，肯定不

It can’t have rained last night, for it is dry outside.

e. 与possibly 连用; 用于as…as one can

Can/could sb. possibly Can he possibly come? What on earth can she possibly mean?

I will come back as soon as I can.

Sb. can't/couldn't possibly 某人不可能

I can't possibly allow you

to go home in this weather. f. 表示惊异，怀疑不相信的态度．(主要用在否定句、疑问句或惊叹句中)如：

Can this be true?

How can you be so rude! This cannot be done by Mary. How can you be so rude!

注意：can 与be able to 区别：

can表能力，只用一般过去

时和一般现在时

be able to表能力+成功，即

最终设法做成了某事。有

各种时态,可以与别的情态动词连用。

The fire spread through the hotel very quickly, but everyone ______ get out.（NMET97）

A. was able to

B. could

C. had to

D. would

g.固定句型

can not … too /can never … too 再也不过分You can never be too careful.

We can never attach too

much importance to balanced diet.

2. may / might

a. 表示允许, might 语气更

委婉

在表示请求、允许时，might

比may的语气更委婉一些，否定回答时要用mustn't，

表示

"不可以"、"禁止"、"阻止"之意．如：

You may drive the car．

--Might l use your pen?

--No，you mustn't .

用May I．．．征询对方许可在文体上比较正式，在口气上比较客气。在日常口语中，用Can I．．．征询对方意见更

为常见。

May I use your ruler?

--- Yes, help yourself. / Yes, you may.

--- No, you mustn’t.

b. 表示可能性, might 语

气更弱

He may feel bored.

He may have read it before.

c. 用于祈使句中表示祝愿。如：

May you succeed!

May God bless you!

d. 用于目的和让步状语从

句中，表强调

I may be slow, but at least

I don’t make mistakes.

Write to him at once, so

that he may know it in time.

e. 固定搭配：may/might as well 不妨，还不如

There’s no bus. We may as well go home on foot now. may well 很有可能

What you say may well be true.

f. 用于虚拟语气中

Had they known what was coming next, they _______ second thoughts.(2012浙江高考19)

A. may have

B. could have

C. must have had

D. would have had