1、 情態(tài)動詞 概說：情態(tài)動詞表示說話人的語氣和情態(tài)，需要，可能，愿意和懷疑等。情態(tài)動詞有一定的詞義，但不完整，必須和主要動詞的原形一起構(gòu)成謂語。常用的情態(tài)動詞有：can, could, may, might, must, have to, ought to, need, dare, shall, will, should, would, be able to, etc.一. can , could, be able toI. 1) can 表示體力或腦力方面的能力，或根據(jù)客觀條件能夠做某事的能力。 A blind man can not judge color. He can speak fiv

2、e languages. 2) 表示許可，在疑問句中表示要求，否定句中 表示不許。 Can (May) I come in ? - Can I use your dictionary? - Of course, you can. This kind of thing cant go on. 3) 表示可能性，常用于疑問句和否定句中，指“某事是否是事實”。Can it be true? Can the hall seat a thousand people? Someone is knocking at the door. Who can it be?She cant be here. He c

3、ant be serious.Mary cant have gone there alone.4) 表示溫和的命令或批評 You can go and fetch some water. You can clean the windows first. You could read more in future. You could be more careful.5) be able to與can 的比較A) 表示能力時可通用No one can / is able to do it. Can you come tonight? /Will you be able to come tonig

4、ht?B) be able to可用于任何時態(tài)， can只能用在現(xiàn)在時或過去時（ could ）中。Im sorry I havent been able to answer your letter.He says / said he will / would be able to come home for Christmas.C) 表示經(jīng)過努而成功地辦到了某個具體的事情時，只能用be able to 不可用 can。With the help of the firemen, they were able to leave the burning house.After years of h

5、ard work he was able to win the prize 2. could 1) could 是can的過去時，除具有can的各種功能外，還可以用來比較委婉，客氣地提出問題或陳述看法。Could you come a little earlier? Im sorry I couldnt lend you the book now.- Could I borrow your bicycle? - Yes, of course, you can. ( 不可用could ) I could come earlier, if necessary.2) can 和could 還可表示某

6、人或某物一時的特點，可譯為“有可能，有時會”。He can be very friendly. He could be very proud.Man can be as cruel as wild beasts. Children could be very trying. (傷腦筋)二. may, might 1） 表示許可，允許，譯為“可以”（正式場合）You may take the book home. People may not pick flowers in the park. Id like to ask a question if I may ask.- May I watc

7、h TV tonight? -Yes, you may. (No, you mustnt/youd better not.)- May I smoke here? - Yes, please. / please dont.2) 表示推測，“或許，可能” 表示一件事或許會發(fā)生，一般用在陳述句中。It may rain tomorrow. They may not be there today. Fools may ask questions more than wise men can answer.Anybody may get ill.注：may 指事實上的可能性, can 指邏輯上的可能性

8、Mr. Smith looks pale. He may be ill.Mr. Smith is in poor health. He can be ill at any time.3) 表示祝愿 May our friendship live long! May you succeed! May you have a good time! May you be happy!4) 常用在目的狀語從句或讓步狀語從句中Get up early so that we may catch the first bus. She went by air that she might /could arri

9、ve earlier.Whoever he may be, he should obey the rules. He would work hard, however rich he might be.5）may well + 動詞原形意為“理應(yīng)，有足夠的理由” may /might as well+ 動詞原形用來建議或勸說某人采取某種行動，有時相當(dāng)于had better常譯為 “還不如,不妨”。He may well be proud of his son. （他大可以他的兒子為榮） She may well say so. （她說得對）It is very late, so you may

10、 / might as well go to bed.Might: might是 may 的過去式，在表示可能時可以換用，但might 可能性較小，或表示更婉轉(zhuǎn)的語氣。 Jim may lend you money. Jim might lend you money.Might I ask a question? Might I ask for a photo of your baby?I wonder if I might borrow some money?三. must, have to, need1. must 的用法： 1） 表示必須要做的事，意為“必須” ，否定式表示不應(yīng)該，不許可

11、禁止等。在回答must的問句時,不用mustnt,而用neednt或dont have to I must leave at 9. We must do everything step by step. We mustnt waste our time. I felt I must call and see him.- Must we hand in our exercises today?- Yes, you must. / No, you neednt. / No, you dont have to.2) must表示“偏要，偏偏”，或“（干嗎）硬要（多指不愉快的事）Why must yo

12、u always interrupt me? Must you go so soon?The car must break down just when we were about to start off.After I give her advice, she must go and do the opposite.3) must也可表示客觀必然性，意為“必然會，總是會” 。 All men must die. Truth must be out. Winter must be followed by spring 3) must 還可表示一種推斷和揣測。must +do對現(xiàn)在事實的猜測;

13、must +have done 對過去事實的猜測.This must be Jims pen. You must be joking. I cant find my key. I must have left it in the bus.The book must have been written by a woman. You must have been thinking of something.2. must與 have to的比較： 1). have to比較強(qiáng)調(diào)客觀需要，表示因客觀環(huán)境或事態(tài)促使而不得不做某事；must強(qiáng)調(diào)主觀看法，表示主觀上認(rèn)為有必要做某事。I must lea

14、rn another foreign language. You have to learn another foreign language if you want to work here.You must be back before 10 oclock. You have to be back before 10 oclock because the train is to leave at 10: 15.2) have to多表示義務(wù)或習(xí)慣動作； must 則表示一種重要或急迫的事情。You have to care for the young. She has to be at t

15、he office before eight every day. You must go to the manager at once, or youll be dismissed. 3） have to可用于不同時態(tài)，可同其他情態(tài)動詞 連用，而must則只有一種形式. We will have to buy another TV set. She is always having to make decisions. He has had to reconsider his position. She may have to stay there longer. I have to /mu

16、st leave now.3. need 的用法： 1）作情態(tài)動詞用時，多用于疑問或否定句中?；卮餹eed提出的問句時，肯定常用must否定常用neednt / dont have toYou need not do anything here. He never need know. She need hardly say anything to him. I dont think he need come. Need I repeat it? There need be no hurry, need there? - Need I go so soon? - Yes, you must.

17、/ No, you neednt. / No, you dont have to. 2) need作情態(tài)動詞用時，也常用在if，或unless 引導(dǎo)的條件狀語從句或wonder后面的賓語從句。 If I need start early, I will. I wonder whether I need advise him. I wont write to her unless I need write to her.3）need have +過去分詞，表示不必做謀事，但 卻做了,有責(zé)備之意;didnt need / have to do表 示不必做且沒做 You neednt have to

18、ld them about it.I invited only two guests, so you neednt havebrought so much food.I didnt have to / didnt need to get up early on Sunday, so I stayed in bed until 8 oclock.need用做行為動詞時的用法：1) need to do ; need doing ; need to be done 的用法I need to buy a new dictionary. My bike needs to be repaired / r

19、epairing.2) 在will或 shall 表示的將來時中need常用做行為動詞。You will never need to worry about him. You will need to say nothing 四. will 和 would 的用法：1. 表示意愿意志和決心或固執(zhí)，用于非人主語時，表示固有性質(zhì)，傾向She wont lend me the money. He is the man who will go his own way.Ill never play a joke on him. I wont argue with you.The window wont

20、open. The door wont shut.2. 表示客觀事實Fish will die out of water. Oil will float on water.3. 表示一種揣想，用于二，三人稱It will be Mr. Wang knocking at the door. She will have heard of the accident.Sorry to be late. You will have been waiting for some time. You will not be familiar with these rare plants.4. 用于疑問句表示邀

21、請或請求Will you give me a piece of paper? Wont you come in and have a little wine?Would you please tell me your telephone number?5. 表示“諾言” ，“命令” ，“叮囑” ，“強(qiáng)迫” 譯為“保證/ 保證不， 必須，一定要We will pay back the money soon. I wont do it any more, I promise you.Youll wait here till I come back. No one will leave the ex

22、amination room before 12 oclock.All will arrive before 7:45. You will finish it before you leave.6. 表示意圖或允諾You will have your share. I will trouble you for the dictionary.7. 表示拒絕，用wontI wont listen to your nonsense. The dog wont stop barking.8. would與 will的用法基本相同，would是will的過去式。如：will表示習(xí)慣而would過去習(xí)慣；

23、用在疑問句中would比will語氣更溫婉等差異。I told him that I would go along with him. Im afraid the journey would be too expensive.Would like something to eat? When I was a child, I would go swimming every summer.五. shall, should, ought 的用法 A) shall的用法1. 用于一，三人稱， 表示征求意見或請求指示。Shall I turn on the light? Shall we meet i

24、n the evening?Shall I come in？（你要我進(jìn)來嗎？） May / Can / Might I come in?（我可以進(jìn)來嗎）Shall they come in or wait outside? Shall he come to see you?Shall + he /she / they +do sth = Do you want him / her / them to do sth2. 用于二，三人稱，表示決心，意志，允諾，命令， 警告，威脅，命運或必然的結(jié)果等。You shall have my answer tomorrow.（允諾） You shall b

25、e sorry for it one day. （ 警告）You shall leave the room or Ill shoot. （ 警告） They shall do as I tell them. （ 命令或吩咐）Nothing shall stop us from carrying out this plan. You shall not smoke here. （命令或禁止）Death is certain to all; all shall die. 死必臨萬物；萬物皆會死 （命運） Who touches pitch shall be defiled. 玩火者必自焚 （必然結(jié)

26、果）B) should的用法1. 表示勸告，建議，應(yīng)該做，且有一種道義上的責(zé)任。You should study the article carefully. Such a thing shouldnt be allowed to happen again.I should help him because he is in trouble now. You should do it because you have promised to.2. 表示對現(xiàn)在，將來，過去情況的某種推測，譯為 “可能，應(yīng)該，該”。He should arrive at noon. Jim should be at

27、 home now.They should have finished the work by tomorrow. They should have reached the town by now.3. 用于委婉，謙虛的提出意見，請求建議。I should say it would be better to try it again. I should think you are right.Id like to have a talk with you. 4. 用于疑問或感嘆句中，表示意外，驚異等情緒，與what, how, why, who連用，且問句不需回答，有些相當(dāng)于修辭性問句。Why

28、 should I fear? (=I dont fear at all.) What should I see but misery? = I could see nothing but misery.)Should we stand by and do nothing? Should you be so silly?5. 在某些從句中，表示驚異，不以為然等情緒?？勺g為“竟然” ；用在獨立的that從句中，這時，that從句已成為感嘆句，可視為省略了Im sorry等；用在結(jié)果狀語從句中，表示“竟會”That things should come to this! 竟落到這種地步！ That

29、 a man should be cruel! 人竟會如此殘忍！What have I said that you should get angry? 我說了什么竟使你生氣了？ It seems so unfair that this should happen to me.It wasnt right that such near neighbors should not know one another.6. 用來表示虛擬（should + do / should + have done） 1）句中有表示命令，請求，建議，堅持等意義時， 名詞性從句中的謂語動詞要用虛擬(should + d

30、o)The teacher suggested that we should practice speaking English as much as possible.My suggestion is that you should go with us. It is suggested that we should start work at once.He made a suggestion that we should help the poor.2）在下面結(jié)構(gòu)的主語從句中 It is important / necessary / natural / strange / a pity

31、 etc用虛擬 (should + do)It is important that we should study another foreign language.It is a great pity that she should have failed to see such a wonderful performance.3) 在lest, for fear that, in case引起的狀語從句中， 謂語動詞用(should + do)He clears the glass with care for fear that he should break it. Be quiet i

32、n case you should wake the baby.They spoke in whispers lest they should be heard.4) should + have done表示過去應(yīng)該做某事卻沒做。含有“責(zé)備，內(nèi)疚”之意。She should have helped you a lot. You should have told him about it.They should / ought to have come back yesterday.六. dare的用法1）dare 用作情態(tài)動詞常表示現(xiàn)在或?qū)頃r間，有時也可表示過去，可用于肯定句，否定句，疑問句

33、或if,unless等引導(dǎo)的從句He dare go deep into the mountains alone. She dare say what she thinks.He dare not criticize her. She never dare speak in public.No one dare go there. How dare you do such a thing?Dare you go home alone? I wonder if she dare come home.I wonder whether she dare disclose the secret.2)

34、dare 用作行為動詞時常用作及物動詞，表示“敢于，敢冒，敢于面對，向挑戰(zhàn)”后可跟名詞，代詞或不定式He dares any difficulties. He dares me to jump over the wall. 他向我挑戰(zhàn)跳過那堵墻I dare you to do it. 量你也不敢 He dared to swim in the river.She didnt dare to tell her mother about it. I wonder how he dared to say so注：Dare同 shall, will, should, would, have, had等

35、連用時，常用作行為動詞. I will not dare to climb the tree. He would never dare to do it.They have never dared to swim in the lake.七. 情態(tài)動詞+動詞完成式的用法1. may和might +動詞完成式1）常用于推測過去的行為，表示“可能已經(jīng)” He may have received the letter. It might have happened last October.2）也可表示將來某時之前的情況 He may have left when you get there. She might have died before he returns.3）表示現(xiàn)在已經(jīng)完成的情況 He might have arrived now. She may have got up now.2. can / c