高中语法专练：viii. 情态动词表示推测

viii. 情态动词表示推测

1. 几乎所有的情态动词都可以用来表示推测，只是各自的语气强弱和所使用的场合不同。

2. 情态动词表示推测，其可能性由低到高的排序为：

might → may → could → can → should → ought to → would → will → must(= will certainly).

注意：

1）might和may表示对具体情况把握不大的推测。

2）could和can多用于疑问和否定句中表示推测。

3）must仅用于肯定句中，表示十分有把握的推测。

4）should可以表示按照常理推测所得出的结论，即“理应”。

5）will表示按照逻辑推理势必会发生的事情。

3. 情态动词表示推测的时态变化形式：

4. “情态动词+动词原形”表示对现在推测时需注意的问题：

1）“can +动词原形”，表示对现在的推测时，一般用于否定句和疑问句。

Can this be true?

这可能会是真的吗？

He can't be in the room, for the door is locked.

他不可能在房间里，因为门是关着的。

2）“could +动词原形”，表示对现在，也可以表示对过去的推测，可用于肯定句。

It could be true.

那可能是真的。

I could drop in later.

我随后可能顺便来访。

3）“may +动词原形”意为“或许，可能”，一般用于肯定句的推测。

I hear she may have some good books.

我听说她可能有些好书。

Jim may lend you some money.

吉姆可能借给你一些钱。

4）“might +动词原形”，表示的可能性比may小。

It might rain this evening, but who knows that?

今天晚上或许会下雨，但是谁知道呢？

I thought you might like to read something, so I have brought some magazines to you.

我以为你可能想读一点东西，因此给你带来了几本杂志。

5）“should +动词原形”，表示可能或期待；ought to表示的可能性更大。

—When can I come for the photos? I need them tomorrow afternoon.

—They should be ready by 12:00.

——我什么时候来取照片呢？我明天下午要用呢。

——十二点以前应该可以取了。

His train arrives at 9 o'clock, so he ought to be here at 9:30.

他的火车九点到，因此他应该在九点半到这里。

She should be home by now, but she isn't.

现在她应该在家，但是却不在。

6）“would/will +动词原形”，表示可能时，will可能性更大。

It will be Mr. Wang knocking at the door.

那会是王先生在敲门。

It would be about 10 o'clock when he left home.

他离开家的时候时间可能是十点钟。

I'm afraid the journey would be too expensive.

恐怕那次旅行太贵了。

7）“must +动词原形”，意为“一定，肯定”，只用于对现在情况有把握的肯定推测。

You must be hungry after 6 hour's long walk.

长途跋涉六个小时后你一定饿了。

She must be sleeping, for the light has gone out.

她一定在睡觉，因为灯都熄了。

注意：

1）若表示有把握的否定推测用can't。

The news can't be true.

这个消息肯定不是真的。

2）must表示对现在情况的推测时，其反意疑问句陈述部分的谓语若是must be，就用isn't/aren't反问, 否则用don't/doesn't反问。

He must be at home, isn't he?

他肯定在家，是吗？

She must be reading in the room, isn't she?

她肯定在房间里读书，是吗？

Tom must live in this area, doesn't he?

汤姆一定就住在这个地区，是吗？

专项练习

1. A computer _______ think for itself; it must be told what to do.

A. can't

B. couldn't

C. may not

D. might not

2. —The lecturer was a tall thin man with white hair.

—Then it _______ Dr. Fell because he is short and fat. It _______ Dr. Jones; he is thin.

A. can't be; must be

B. couldn't have been; might have been

C. must be; can't be

D. can't have been; must have been

3. There is no parking in front of the post office. You _______ park here.

A. oughtn't

B. can't

C. didn't

D. wouldn't

4. She _______ be a good language teacher, but she can't be a language expert.

A. will

B. can

C. should

D. is to

5. “This _______ be hers. It _______ be mine.” He said firmly.

A. can't; may

B. can't; must

C. must not; can

D. can't; can

6. 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

7. Peter _______ come with us tonight, but he isn't quite sure.

A. must

B. may

C. can

D. will

8. Whatever your problems _______ be, they can't be worse than mine.

A. will

B. should

C. may

D. can

9. —Will the test be difficult?

—I think it _______ be easy enough for all of us to pass, but I'm not sure.

A. must

B. can

C. may

D. will

10. —Will your brother stay at home tonight？

—I'm not quite sure. He _______ to see the film this evening.

A. may be going

B. can go

C. may go

D. must go

11. Look at the clouds. It _______ rain.

A. must

B. was going to

C. may

D. will

12. You _______ lead a horse to the water, but you _______ not make it drink.

A. will; can

B. may; can

C. may; dare

D. dare; can

13. —Do you think the flight is delayed?

—It _______ be, especially in such weather.

A. would

B. should

C. might

D. ought to

14. —Are you coming to Jeff's party?

—I'm not sure. I _______ go to the concert instead.

A. must

B. would

C. should

D. might

15. Will you answer the phone? It _______ be your mother.

A. might

B. will

C. shall

D. need

16. Now that you've got a chance, you _______ as well make full use of it.

A. can

B. should

C. need

D. might

17. Since the flight has been cancelled because of the bad weather, we _______ go by train.

A. ought to have

B. had better to

C. might as well

D. would rather not

18. It's nearly seven o'clock, Jack _______ be here at any moment.

A. must

B. need

C. should

D. can

19. In case I _______ , I would try again.

A. will fail

B. would miss

C. should fail

D. shall miss

20. —That must be a mistake.

—No, it _______ a mistake.

A. must not be

B. needn't

C. can't be

D. would not be

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