高中語法專練：viii. 情態(tài)動詞表示推測

viii. 情態(tài)動詞表示推測

1. 幾乎所有的情態(tài)動詞都可以用來表示推測，只是各自的語氣強弱和所使用的場合不同。

2. 情態(tài)動詞表示推測，其可能性由低到高的排序為：

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

注意：

1）might和may表示對具體情況把握不大的推測。

2）could和can多用于疑問和否定句中表示推測。

3）must僅用于肯定句中，表示十分有把握的推測。

4）should可以表示按照常理推測所得出的結(jié)論，即“理應”。

5）will表示按照邏輯推理勢必會發(fā)生的事情。

3. 情態(tài)動詞表示推測的時態(tài)變化形式：

4. “情態(tài)動詞+動詞原形”表示對現(xiàn)在推測時需注意的問題：

1）“can +動詞原形”，表示對現(xiàn)在的推測時，一般用于否定句和疑問句。

Can this be true?

這可能會是真的嗎？

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

他不可能在房間里，因為門是關(guān)著的。

2）“could +動詞原形”，表示對現(xiàn)在，也可以表示對過去的推測，可用于肯定句。

It could be true.

那可能是真的。

I could drop in later.

我隨后可能順便來訪。

3）“may +動詞原形”意為“或許，可能”，一般用于肯定句的推測。

I hear she may have some good books.

我聽說她可能有些好書。

Jim may lend you some money.

吉姆可能借給你一些錢。

4）“might +動詞原形”，表示的可能性比may小。

It might rain this evening, but who knows that?

今天晚上或許會下雨，但是誰知道呢？

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

我以為你可能想讀一點東西，因此給你帶來了幾本雜志。

5）“should +動詞原形”，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.

——我什么時候來取照片呢？我明天下午要用呢。

——十二點以前應該可以取了。

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

他的火車九點到，因此他應該在九點半到這里。

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

現(xiàn)在她應該在家，但是卻不在。

6）“would/will +動詞原形”，表示可能時，will可能性更大。

It will be Mr. Wang knocking at the door.

那會是王先生在敲門。

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

他離開家的時候時間可能是十點鐘。

I'm afraid the journey would be too expensive.

恐怕那次旅行太貴了。

7）“must +動詞原形”，意為“一定，肯定”，只用于對現(xiàn)在情況有把握的肯定推測。

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

長途跋涉六個小時后你一定餓了。

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

她一定在睡覺，因為燈都熄了。

注意：

1）若表示有把握的否定推測用can't。

The news can't be true.

這個消息肯定不是真的。

2）must表示對現(xiàn)在情況的推測時，其反意疑問句陳述部分的謂語若是must be，就用isn't/aren't反問, 否則用don't/doesn't反問。

He must be at home, isn't he?

他肯定在家，是嗎？

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

她肯定在房間里讀書，是嗎？

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

湯姆一定就住在這個地區(qū)，是嗎？

專項練習

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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