语法专题六：情态动词.doc

语法专题六：情态动词
1. 常见情态动词及用法说明
情态动词
用法说明
can

1) 表示主观能力；2) 表示许可、请求；
3) 表示可能性、推测，主要用于否定句、疑问句中。
习语：can’t help doing；can’t (help) but do(不能不、只能)
could
为can的过去时，具备can的各种功能，语气更委婉、客气。
be able to
1) 表示已能成功做到某事；2) 可用于各种时态。
may

1) 表示许可，允许；2) 表示可能性、推测；3) 表示祝愿（置于句首）；
4) 其一般疑问句的否定回答常用: No, …can’t.
习语：may well (not) do[很（不）可能]；may as well (not) do(不妨)
might
为may的过去时,具备may的各种功能,语气更委婉,可能性更小。
must

1) 表示主观上认为“必须”，如为一般疑问句，其否定回答常为： No, …needn’t / …not have to.
2) 表示“偏偏、偏要”；3) 表示肯定的推测或必然。
have to
1) 强调客观上“不得不”；2) 可用于各种时态。
should

1) 表示道义上的责任； 2) 用于疑问句或感叹句中，表示意外、惊异；
3) 表示“按常理推断理应”；
4) 用于 “Who should do…but”结构中，表示“除了……还有谁会”。
ought to
与should同义，语气略重；注意其疑问式和否定式。
shall

1) 用于第一人称，表示征求意见、请求；
2) 用于第二、三人称，表示说话者的意志、允诺、命令、威胁等。
3) 用在法律、条款、协定等文件中，表示义务、规定等。
will

1) 用于第二人称，表示征求意见、请求；
2) 表示习惯；would则表示过去的习惯（只表重复动作，不表状态；used to
则皆可）；3) 表示意志、决心；4) 用于if条件从句中，表示意愿。
would
为will的过去式，表示请求时，语气更委婉。
need

“需要”的意思，常用于否定句、疑问句中，无人称、时态变化，后接动词原形，否定式为needn’t。
dare
“敢于”的意思，常用于否定句、疑问句中，无人称变化，但有时态变化，
其过去式为dared, 否定式为dare/dared not, 后接动词原形。
习语：I dare say / I daresay: 我想，我认为
2. 情态动词表示推测
1) 表示肯定的推测，用must + do / have done(过去或完成) / be doing(进行)；
2) 表示否定的推测或用于疑问句中，用can，用法同上；
3) 表示可能性的推测，用may，同法同上。
注意：以上句子的反义疑问句要根据该句的实际时态来定。
巩固练习：
1. Ding Junhui ______ the championship; He didn’t pass the first round.
A. might not have won B. shouldn’t have won
C. couldn’t have won D. mustn’t have won
2. Children under 12 years of age in that country ______ be under adult supervision when in a public library.
A. must B. may C. can D. need
3. I am sure you’d rather he stayed in Spain, ______?
A. wouldn’t you B. aren’t I C. didn’t he D. hadn’t you
4. ---Could I borrow your pencil?
---Of course, you ______.
A. can B. may C. could D. might
5. You ______ to the meeting this morning if you have something important to do.
A. needn’t to come B. don’t need come C. don’t need coming D. needn’t come
6. I promised to get there before 5 o’clock, but now the rain is pouring down. They ______ for me impatiently.
A. may wait B. ought to wait C. could wait D. must be waiting
7. I’ve decided to take the job and I ______ change my mind.
A. mustn’t B. can’t C. won’t D. may not
8. I ______ up early this morning. So I stayed in bed till 9 a. m.
A. needn’t have got B. didn’t need to get C. shouldn’t have got D. can’t have got
9. The flower is dead. I ______ it more water.
A. will give B. would have given C. must give D. should have given
10. It is natural a man as old as he ______ be very forgetful.
A. can B. must C. should D. would
11. The dog barked fiercely, but no one ______ over to stop it.
A. could go B. dare go C. dared go D. might go
12. We ______ hurry if we want to arrive in time.
A. must B. need C. may D. have to
13. He ______ get up early when he lived in the countryside.
A. would B. will C. mustn’t D. can’t
14. ________ you please pass on a message to him?
A. Do B. Shall C. May D. Will
15. ---Could I call you by the first name?
---Yes, you ______.
A . will B. could C. may D. might
16. The fire spread through the hotel very quickly but everyone ______ get out.
A. had to B. would C. was able to D. could
17. It’s nearly seven o’clock. Jack ______ be here at any moment.
A. must B. need C. should D. can
18. ---I think Helen is at home.
--- No, she ______ be at home, for she phoned me from the airport just five minutes ago.
A. mustn’t B. needn’t C. can’t D. daren’t
19.  He’s late. What ______ have happened to him?
A. can B. may C. should D. must
20. After I gave her my advice, she ______ go and do the opposite.
A. should B. must C. shall D. ought
21. Who ______ come in but the president himself!
A. may B. should C. can D. shall
情态动词：CAAADDCBDCCAADCCCCDBB

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