情态动词

北京四中　　毕　勤

　　一、 知识要点
　　1．can ( could)
　　1)能, 会 (表示能力 = be able to )
　　He listened, but could hear nothing.

　　2)可能, 会 (表示怀疑或不确定性, 用于否定, 疑问,或感叹句)
　　It can’t be true.
　　How can you be so careless!

　　3)可以 (表示允许, 但不如may 正式)
　　—Can I smoke here?　
　　—Of course, you can.

　　4)区别 can / be able to
　　形式上: can 只有两种时态can / could, 但是be able to 有很多种
　　I shall be able to tell you about it tomorrow.
　　She has not been able to come to school for a whole week.

　　意思上: can 是一种客观存在的可能；be able to 是拥有能力并使用, 经过一番努力使之成为能力
　　Marx kept on studying English and using it until he had mastered it so well that he was able to write one of his great works in English.
　　He could swim, but he didn’t jump into the water to save the girl.

　　2．may ( might)
　　1)可以 (表示允许, 许可= be allowed to )
　　—May I come in?
　　—Yes, please.

　　2)在否定句中, 通常用mustn’t 或be not allowed to 来代替may not, 表示 “禁止, 不可以”
　　You mustn’t smoke here.
　　You are not allowed to smoke here.

　　3)可能, 或许 (表示可能性, 一般用于肯定句)
　　He might be working in the office now.
　　He might have been a passenger’s child and he needed no ticket at that gate.

　　3．must
　　1)必须, 应该 (表示有做一动作的必要或义务 = be obliged to , have to)
　　We must work, and above all we must believe in ourselves.

　　2)一定, 准是(表示推测，用于肯定句中)
　　He must be a milkman.

　　3)needn’t 或don’t have to (haven’t got to )的意思是“不必”, 而mustn’t 的意思是“不允许、决不可以、不应该”
　　You needn’t be back by 10 o’clock.
　　You don’t have to be back by 10 o’clock.
　　You mustn’t make any noise at this time.

　　4)区别 must / have to
　　形式上: must 一种形式, have to 有多种时态 don't have to = needn’t have to = must

　　意思上: must主观, have to客观　　
　　We must do the work well.
　　In some cities, some people have to wear masks.

　　4．ought to（to不可丢） 应当, 应该
　　1)表示有义务应该做某事, 还可以表示劝告或责备
　　I ought to visit my sick friend more often.

　　2)“ ought to have done”表示原本应该做而没做
　　You oughtn’t to have quarreled with him.

　　5．shall
　　1)用于第一、三人称的疑问句中, 表示说话人征求对方的意见或向对方请示
　　Shall I open the window for you?
　　Shall we begin our lesson?
　　When shall he be able to leave the hospital?

　　2)用于第二、三人称的肯定句中, 表示说话人给对方的命令, 警告, 允诺或威胁
　　You shall go at once! (命令)
　　You shall fail if you don’t work harder. (警告)
　　He shall have the book when I finish reading it. (允诺)
　　He shall be punished. (威胁)

　　6．should
　　1)应当, 应该(同ought to)
　　You shouldn’t judge a stranger always by the clothes he wears.

　　2)should have +done表示应该做某事而实际上是没做
　　You should have been here ten minutes ago.

　　3)shouldn’t have + done 表示不应该做某事而实际上做了
　　You shouldn’t have got up so late.

　　4)用于虚拟语气的某些句型中
　　I suggested that we (should ) go out for a walk.

　　7．will
　　1)用于各人称, 不仅表示将来的时态, 而且表示有做某事的意志, 意愿, 决心或打算
　　I won’t take up too much room.
　　在条件状语从句中will 是情态动词, 表示意愿或决心
　　If you will go into the fields and turn over some stones, you are sure to uncover a city of ants.

　　2)在疑问句中用于第二人称时, 表示说话人向对方的有礼貌的请求
　　Will you give me a piece of paper?
　　Will you open the window?

　　8．would
　　1)在疑问句中用于第二人称时, 表示说话人向对方的有礼貌的请求, 较will婉转客气
　　Would you please let me keep my hands in my pockets?

　　2)表示过去习惯性的或反复发生的动作 (而used to do表示强调对比)
　　Every morning he would go for a long walk.
　　She used to live in the countryside. But now she didn’t.

　　9．need
　　1)当情态动词时, 用于否定和疑问句, 在肯定句中用must, have to, ought to 或should.
　　—Need I do that right now?
　　—Yes, you must. ( No, you needn’t)
　　You needn’t worry about her. She will know how to take care of herself.
　　We needn’t go so early, need we?

　　2)needn’t have done 表示本不必做某事而实际上做了某事的意思
　　You needn’t have waited for me.

　　3)need作实义动词后接to do, 表示与主语的关系是主动的，若与主语的关系是被动的则接doing / to be done
　　I need to have a rest.
　　The flowers need watering / to be watered.

　　10．dare
　　当情态动词时, 用于否定和疑问句和条件句, 有过去式
　　How dare you say I’m not fair?
　　They said he dared not come.

　　二、练习检测
　　1. — ______ we hand in our work this afternoon?
　　　 — No, you needn’t.
　　A. Need　　 B. Must　　 C. Will　　 D. May

　　2. It must have rained last night, ______ it?
　　A. couldn’t　　 B. mustn’t　　 C. didn’t 　　 D. hasn’t

　　3. Only when the rain stopped ______ to go back home.
　　A. he was able　　 B. could he　　 C. can　　 D. was he able

　　4. I wonder how ______ say such a thing.
　　A. he dare　　 B. he dared　　 C. dare he　　 D. he dares

　　5. — May I ask you one more question?
　　　 — Certainly, you ______.
　　A. might　　 B. may　　 C. can　　 D. do

　　6. — I think Helen is at home.
　　　 — No, she ______ be at home, for she phoned me from the airport just now.
　　A. mustn’t　　 B. needn’t　　 C. can’t　　 D. dared not

　　7. Hurry up! Tom ______ for us at the gate.
　　A. must wait　　　　　　　　 B. must be waiting
　　C. can be waited　　　　　　 D. must have waited

　　8. — ______ he come in?　　　
　　　 — Yes, please.
　　A. Will　　 B. Does　　 C. Shall　　 D. Would

　　9. He was taken away by the police. He _______ for a thief.
　　A. must have mistaken　　　 B. must have been mistaken
　　C. must be mistaken　　　　 D. must mistake

　　10. Let’s watch TV, ______?
　　A. won’t　　 B. will you　　 C. shall we　　 D. do you

　　11. Let us go swimming now, ______?
　　A. shall we　　 B. don’t we　　 C. do you　　 D. will you

　　12. If you ______ to the cinema with me, I’ll buy a ticket for you.
　　A. will go　　 B.went　　 C. shall go　　 D. ought to go

　　13. — ______ you like to see a film?
　　　　— Yes, ______.
　　A. Would; I’d like to　　　　B. Will; I will
　　C. Should; I should　　　　　 D. Would; I would like to see

　　14. You must be a writer, ______ you?
　　A. mustn’t　　 B. can’t　　 C. are　　 D. aren’t

　　15. We must obey the rules, ______?
　　A. mustn’t we　　 B. didn’t we　　 C. haven’t we　　 D. don’t we

　　16. He used to live in the country, ______ he?
　　A. usen’t 　　 B. usedn’t　　 C. did　　 D. does

　　17. Night has fallen. We have to go home, ______ we?
　　A. don’t　　 B. haven’t　　 C. mustn’t　　 D. shouldn’t

　　18. ______ you close the door for me? It’s so cold.
　　A. Shall　　 B. Should 　　 C. Will 　　 D. Must

　　19. You should get up earlier tomorrow morning. You ______ be late for school again.
　　A. couldn’t　　 B. mustn’t　　 C. won’t 　　 D. needn’t

　　20. — Hey! Look what I’ve got for our party, a bottle of wine!
　　　　— You ______ it. We still have two in the cupboard.
　　A. needn’t have bought　　　　　B. couldn’t have bought
　　C. needn’t buy　　　 　　　　　 D. mustn’t buy

　　21. He is happy. He ______ in his examination.
　　A. mustn’t have failed　　　　　　 B. shouldn’t have failed
　　C. needn’t have failed　　　　　　 D. could not have failed

　　22. You ______ clean the window today if they are dirty.
　　A. must　　 B. need　　 C. can　　 D. will

　　23. — Shall I tell John about it?
　　　　— No, you ______. I’ve told him already.
　　A. needn’t　　 B. wouldn’t　　 C. mustn’t　　 D. shouldn’t

　　24. Don’t throw the bottle away. It _______ in the future.
　　A. might be needed　　　　B. may need
　　C. is needed　 　　　　　 D. shall be needed

　　25. — Would you lend me your bicycle for a while?
　　　　— Sorry, ______.
　　A. I mustn’t　　 B. you wouldn’t　　 C. I can’t　　 D. I’m afraid not

　　26. It is suggested that we ______ everything ready by the end of the week.
　　A. have got　　 B. must get　　 C. should get　　 D. be got

　　27. He ______ harder when he was young.
　　A. had better study　　　　　　 B. must study　　
　　C. should have studied　 　　　 D. should study

　　28. — Who ______ it be?　　　
　　　　— It must be Mr. Wang.
　　A. may　　 B. must　　 C. might 　　 D. can

　　29. The classroom is empty. I think they ______ to the library.
　　A. may go　　　　　　 B. must have gone
　　C. must go　　　　　　D. should have gone

　　30. There was plenty of time. She ______ have hurried.
　　A. wouldn’t　　 B. needn’t　　 C. couldn’t　　 D. mustn’t

　　三、答案
　　1-5 B C D B B　　 6-10 C B C B C　　 11-15 D A A D A　　 16-20 B A C B A

　　21-25 D A A A D　　 26-30 C C D B B

　　四、解析
　　2．在这种句式中若有过去时的状语，反意部分则用过去时，若没有则用hasn’t 或haven’t反问。e.g. It must have rained, hasn’t it?

　　3．only放句首，修饰限制状语时，句子用倒装语序。

　　5．用may提问，用may回答。

　　7．用进行时更侧重此时的状态。

　　9．此句意为“他一定是被错当成了小偷。”

　　10．在Let’s句型中用shall we反问。

　　11．在Let us句型中用will you反问。

　　12．此时的will是情态动词，表“愿意”

　　14．此处must表判断和推测，反意部分看具体的动词

　　15．此处must是情态动词表“应该”，反意部分用mustn’t

　　16．used to 的反意疑问句，可用usedn’t, 也可用didn’t

　　17．have to的否定和疑问式常用助动词do来帮忙。

　　21．此句意为“他不可能在这次考试中没过”。此题可用排除法。

　　22．根据此句后面的条件句断定用must合适

　　24．might be needed 表示不太肯定的判断与推测。

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