情态动词讲解can,may, should,must,ought to区别及用法,,练习加详解(9页).doc

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1、-情态动词讲解can,may, should,must,ought to区别及用法,练习加详解-第 9 页一、情态动词主要用来表示说话人的看法、态度等1. can (could)1) 表示能力，could主要指过去时间。例如： Two eyes can see more than one. 两只眼比一只眼看得清。 Could the girl read before she went to school? 这女孩上学前能识字吗？ 因为can不能和其他助动词连用，所以表示将来式时用will be able to 例：You will be able to skate after you have

2、 practiced it two or three times.注意：Can表示一贯的能力 ，be able to表示客观能力和通过努力可以达到的能力 I cant swim. But I am sure I will be able to swim through more practicing. The fire spread through the hotel, but everyone was able to get out2) 表示允许。例如： Can I have a look at your new pen? 我可以看一看你的新钢笔吗？ He asked whether he

3、could take the book out of the readingroom. 他问他可不可以把书带出阅览室。3) 表惊异、怀疑、不相信等态度。主要用于否定句、疑问句或感叹句中。例如： Where can (could) they have gone to? 他们会去哪儿了呢？ How can you be so careless? 你怎么这么粗心？4) 比较委婉客气地提出问题或陈述看法。例如： Can (Could) you lend me a hand? 帮我一把好吗？. Im afraid we couldnt give you an answer today. 恐怕我们今天不能

4、给你答复。Could/can+have done 结构表示对过去发生的事情的“怀疑”或“不肯定”。 could 加完成式还用于肯定句时一般表过去可能完成而却未完成的动作。Can they have won the basketball match？他们赢了那场篮球赛吗？What you referred to just now can have made her very sad.你刚刚所谈到的可能令他很伤心。You could have completed the task a little earlier.你本来能早点完成任务的。（但事实上并没有提前完成任务）I could have pa

5、ssed my examination easily but I made too many stupid mistakes.我本可以轻易通过考试，但我犯了太多不该犯的错误。如表具体做某一件事的能力时，则须用 be able to .He was able to translate the article without a dictionary.他可以不用词典翻译那篇文章。2may (might) 1) 表允许，might可以指过去时间，也可指现在时间，语气更委婉。例如： You may take whatever you like.你喜欢什么就拿什么。 May (Might) I ask

6、for a photo of your baby? 我可以要一张你宝宝的照片吗？2) 在回答以may引起的问句时，多避免用这个词，而用其它方式，如Yes, please. / Certainly. / Please dont. / Youd better not. / No, you mustnt.等，以免显得太严峻或不客气。3)may /might 推测性用法 可能He may be right. He may not come today (可能不) He may /might come tomorrow.注意 : (1)只用于肯定和否定句中,不用于疑问句中。 (2) might 比may

7、可能性更小 He might get a job. He may get a job. (3) may no 可能不 can not不可能 He may not come . He cant come4)表建议（可和as well 连用）You may（might）as well stay where you are. 你还是原地待着好。（may as well 有“还是的好”的含义）5)表祝愿May you be happy!6). might表过去的“可能”和“允许”多用于间接引语。She said that he might take her dictionary. 她说他可以拿她的词典

8、去用。除在间接引语中外，might一般不表示过去的“可能”与“许可”。表过去的“可能”可用could，表过去的“许可”可用were (was) allowed to。7)might表现在的“可能”，其可能性要比may小。Electric irons could be dangerous; they might give you a severe shock.8)may (might) + have +done 表示对过去发生行为的推测，含有“想必”、“也许是”的意思。It may have been true. 这事也许是真的。He might not have settled the que

9、stion. 他可能尚未解决那个问题。3. must1)表示义务。意为“必须”（主观意志）。例如：We must do everything step by step .我们必须按部就班地做一切事情。Why must you always bother me? 为什么你偏要打扰我呢。2)must be + 表语的结构，通常表示猜测，含有“一定”之意。（只用在肯定句中）He must be an honest boy.他一定是个诚实的男孩This must be your room.这一定是你的房间。3)must 的否定式有两个：当回答由must引起的问题时，否定答复要用neednt或dont

10、have to 表示“不必”、“无须”、“用不着”、“不一定”的意义。当表示“不应该”、“不许可”、“禁止”时，就用must not。Must I go tomorrow?明天我必须去吗？Yes, please. No , you neednt. 4)must +have +过去分词的结构，常用在肯定句中，表示对过去发生行为的推测，含有“一定”、“准是”的意思。否定和疑问句用can。She must have studied English before.她以前一定学过英语。5) 区别：have to的含义与must是很接近的,只是have to 比较强调客观需要，must着重说明主观看法。I

11、 must clean the room.（主观想法） I have to clean the room.（客观需要）另外，have to 能用于更多时态：We had to be there at ten .我们得在十点钟到那里。We will have to reconsider the whole thing.have to 的否定式：dont have to do 表示“不必做”之意。4.shall 1) 表征询意见，用于第一、第三人称疑问句。例如： Shall I get you some tea? 我给你点茶好吗？ Shall the boy wait outside? 让那男孩在

12、外面等吗？2)表说话人的意愿，有“命令、允诺、警告、决心”等意思，用于第二、第三人称陈述句。例如： You shall do as I say. 按我说的做。（命令） You shall have my answer tomorrow. 你明天可以得到我的答复。（允诺） He shall be sorry for it one day, I tell you. 有一天他会后悔的，我告诉你。（警告） Nothing shall stop us from carrying out the plan. 什么也不能阻止我们执行这项计划。（决心）5. should1)用于第一人称疑问句中询问对方的意愿，

13、但语气较委婉温和，如：What should we do now? 我们现在该怎么办？2)表示应该、必须，常与must 换用。例如：We should (must) master a foreign language at least.3）（表示不确定）万一。例如： If I should see him, Ill tell him. 万一我见到他，我就告诉他。 If it should rain tomorrow, the sports meeting would be postponed. 万一明天下雨。4)“should+be+表语”的结构，表示推测或惊奇。例如：They should

14、be back by now. 他们现在应该回来了吧。I am sorry that she should be so careless. 我感到遗憾她竟会那样粗心。5)“should+have+过去分词”的结构，表示过去该做而实际上尚未做的动作或行为；其否定则表示发生了不应该发生的行为。其同义结构“ought to have +过去分词”,表示过去“早应该”、“本当”之意，语气较强。例如：I should have thought of that. 这一点我是应当想到的。（但没想到）They should not have left so soon.他们不应当走得这么早。（但已走了）6) 在

15、“It is natural (strange, natural, necessary, surprised, impossible, important ) that”句型中，主语从句中的谓语动词要用should +动词原形”表示“理所当然”、“奇怪”、“必要”、“惊异”等的意思。在lest（以免）、for fear (that) (以防)、in case（以备万一）等之后也要用should+动词原形;在advise, sugest, order, demand, request 等的从句中should+do”例如：It is necessary that he(should) be sen

16、t there at once.It is strange that he should say so. 他会说这样的话真是奇怪。6.will和would的用法1）表示意志，决心或愿望。例如：Surely we will support all the people in the world in their struggle for peace.He would not let me try it . 他不肯让我去试。2）will表示经常性、习惯性、倾向性，would表示过去的习惯行为。He will sit there hour after hour looking at the traf

17、fic go by.He would come to see me when he was in Beijing.3）用于第二人称作主语的疑问句中，表示对对方的请求，would的语气比will委碗Would/will you kindly tell me the way to the station? 请问到火车站怎么走？4）表可能性This will be the book you are looking for. 这可能就是你要找的书。She would be about 60 when she died.7.ought to 表义务，意为“应该”（因责任、义务等该做），口气比should

18、稍轻。例如： You are his father. You ought to take care of him.你是他父亲，应当管他。 You oughtnt to smoke so much. 你不应该抽这么多烟。8. used to1）表示过去的习惯动作或状态，现在不复发生或存在。疑问式和否定式有两种。例如：i There used to be a building at the street corner, but it has been pulled down. I usednt (didnt use) to smoke. 我过去不抽烟。j F Used you (Did you u

19、se) to go to school on foot? 你过去常步行去学校吗？2）used to +v, be used to +v-ing和be used to +v used to +v意为“过去常常”，“过去一直”；be used to +v-ing / n（名词）意为“习惯于”；be used to +v意为“被用来（做某事）”。例：He used to smoke. Now he doesnt. Hes quite used to hard work / working hard.The knife is used to cut bread.9.特殊情态动词need和dare的用法

20、：need和dare既可用作情态动词，也可用作实义动词。用作情态动词时，主要用于否定句和疑问句。用作实义动词时，可用于各种句式。need 情态动词 实义动词现在时You need (not) do He need (not) do You (dont) need to do He needs (doesnt need) to do 过去时You needed (didnt need) to do He needed (didnt need) to do将来时You need (not) do He need (not) do You will (not) need to doHe will (

21、not) need to dodare 情态动词 实义动词现在时 dare to/darent/dare not doDare he do? dare/dares to dodo/does not dare (to) doDo you/Does he dear (to) do?过去时dared to/dared not doDared he do? dared to do/did not dare (to) doDid he dare (to) do1) 用作情态动词。例如：|You neednt telephone him now. She dare not go out alone at

22、night. 她晚上不敢一个人出去。2) 用作实义动词。例如：You dont need to do it yourself. I dare say hell come again.我想他会再来（I dare say为固定二、 情态动词表推测：1.can 表示可能（理论上或是逻辑判断上）。例如：,_K He cant (couldnt) have enough money for a new car. 他不可能有足够的钱买新车。 You mustnt smoke while youre walking around in the wood. You could start a fire. 在林

23、子里走时勿吸烟，那样可能会引起火灾。2.may 表可能（事实上）。可以指过去时间，也可以指现在时间，但语气更加不肯定。 He may be at home. 他可能在家。 She may not know about it.3. must 表示揣测。意为“想必、准是、一定”等，只用于肯定句。 He must be ill. He looks so pale. 他准是病了。他的脸色苍白。 Shes wearing a diamond necklace. She must have a lot of money. 4. should 表推测，意为“想必一定、照说应该、估计”等。例如： The fi

24、lm should be very good as it is starring first-class actors. 这部新电影是一流演员主演的，估计拍得很好。 They should be home by now. 照说他们现在应当已经到家了。5. ought to 表推测，暗含很大的可能，语气较弱。例如： Han Mei ought to know his telephone number. 韩梅该知道他的电话号码。 Theres a fine sunset; it ought to be a fine day tomorrow. 今天有晚霞，明天应该是个好天。6. could可能性不

25、大，语气较弱。7 might 可能性最小，语气最弱。表示可能性大小的顺序为： must will would ought to should can could may might7.would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情态动词。例如：1）The soldier would sooner die than surrender. The brave soldier would as soon

26、die as yield to such an enemy. Id rather walk than take a bus.If you dont like to swim, you may just as well stay at home.2)would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句，that 常省去，从句要用虚拟语气。对现在和将来的假设用过去时，对过去的假设用过去完成时。例如：I would rather you came on Sunday. I would sooner you

27、hadnt asked me to speak yesterday.8.表推测的情态动词句子的反意疑问句He must/may be in the room, isnt he? He cant be in the room, is he？He must have finished the work, hasnt he? He may have done the work last night, didnt he?结构：1情态动词+ 动词原形 （对现在和将来的动作进行推测）He must understand that we mean business.2情态动词+ be +doing (对正在

28、发生的动作进行推测)-Where is LiLei ? - He may be studying at school.3.情态动词+ have +done ( 对过去的动作进行推测) must have done 一定干了某事 could have done 可能干了某是或本可以干了某事may/might have done 也许已经干了某事 should/ ought to have done 本应该做了某事可是没有做need not have done 本不必干了某事 表示过去做了某事，但没有做的必要，意为“本没必要” You neednt have waken me up; I dont

29、 have to go to work todayhad better have done 最好干了某事 would rather have done 宁愿干了某事would like / love have done 本想干了某事其实未干 Since the road is wet, it must have rained last night.备注：态动词 + have +done 反义问句的结构由有无时间状语来决定。Lucy must have worked last night, didnt she?Lucy must have worked , hasnt she? 4.情态动词+

30、have been + v-ing形式 （表示推测或评论过去某动作是否正在进行或一直在进行）They should have been meeting to discuss the problem.三、情态动词其它用法1. cannot but do sth. 表示不得不，只好 I cannot but choose to go.2. may well +动词原形 完全能， 很可能 He may well be proud of his son.3. may as well 最好 We may as well stay where we are.4 cannot ( 或never 等否定词)与

31、enough 表示再也不为过 You cannot be careful enough.情态动词练习题1. Jack described his father, who _a brave boy many years ago, as a strongwilled manA. would be B. would have been C. must be D. must have been 2.You_ buy a gift, but you can if you want to.A. must B. mustnt C. have to D. dont have to3. I have told

32、you the truth. _ I keep repeating it?A Must B Can C May D Will4. I_ have watched that movie itll give me horrible dreams. A. shouldnt B. neednt C. couldnt D. mustnt5. Mark _ have hurried. After driving at top speed, he arrived half an hour early.A. neednt B. wouldnt C. mustnt D. couldnt 6. _ I take

33、the book out? Im afraid not.A. Will B. May C. Must D. Need7.Just be patient .You _ expect the world to change so soon .A. cant B. neednt C. may not D. whether 8.I havent got the reference book yet, but Ill have a test on the subject next month. Dont worry. You_ have it by Friday.A. could B. shall C.

34、 must D. may 9.May I take this book out of the reading room? No, you_ . You read it in here. A. mightnt B. wont C. neednt D. mustnt10.Doctors say that exercise is important for health, but it _ be regular exercise.Acan Bwill Cmust Dmay11.-Good morning. Ive got an appointment with Miss Smith in the P

35、ersonnel Department. -Ah, good morning. You _ be Mrs. Peters. A. might B. must C. would D. Can12.“You _ have a wrong number,” she said. “Theres no one of that name here.”A. need B. can C. must D. would 13.-Sorry, Professor Smith. I didnt finish the assignment yesterday.-Oh, you _ have done it as yes

36、terday was the deadline.A. must B. mustnt C. should D. shouldnt14. Bob would have helped us yesterday, but he-_A. was busy B. is busy C. had been busy. D. will be busy 15. John went to the hospital alone. If he_ me about it, I would have gone with him.A. should tell B. tells C. told D. had told 16.

37、George is going to talk about the geography of his country, but Id rather he_ more on its culture.A. focus B. focused C. would focus D. had focused17.If we _ the other road, we might have arrived here in time for the meeting. A. take B. had taken C. took D. have taken18.-The weather has been very ho

38、t and dry. -Yes. If it had rained even a drop, things would be much better now! And my vegetables .A. wouldnt die B. didnt die C. hadnt died D. wouldnt have died 19Had I known about this computer program, a huge amount of time and energy . Awould have been saved Bhad been saved C.will be saved Dwas

39、saved20. Its the office! So you_ know eating is not allowed here. Oh, sorry.A. must B. will C. may D. need21. What do you mean, there are only ten tickets? There_ be twelve.A. should B. would C. will D. shall22. I dont care what people think. Well, you _A. could B. would C. should D. might23.I cant

40、find my purse anywhere.You have lost it while shopping.A.may B.can C.should D.would24.It is usually warm in my hometown in March，but it be rather cold sometimes.A.must B.can C.should D.would25.Hows your tour around the North Lake? Is it beautiful?It_ be， but it is now heavily polluted.A.will B.would

41、 C.should D.must26.Whats the name?Khulaifi. _ I spell that for you?A.Shall B.Would C.Can D.Might27.John，look at the time. _ you play the piano at such a late hour?A.Must B.Can C.May D.Need28.Catherine，I have cleaned the room for you.Thanks. You_ it.I could manage it myself.A. neednt do B. neednt hav

42、e done C.mustnt do D.shouldnt have done29.Ill tell Mary about her new job tomorrow.You_ her last week.A.ought to tell B.would have told C.must tell D.should have told30.Excuse me.Is this the right way to the Summer Palace?Sorry，I am not sure. But it_ be.A.might B.will C.must D.can1. D. 考查情态动词推测用法。句意

43、为“杰克把他的父亲描述为一个意志坚强的人，他的父亲多年前肯定很勇敢。”用must have been表示对过去事情的肯定推测。2. D情态动词dont have to 意为“没有必要”，符合语境，句意为：“你没有必要买礼物，但如果你想买的话，你也可以买。”3. A考察情态动词的用法。must 必须, 一定 can 可以, 能够 may 也许 will 意愿, 倾向性动作, 前半句说我告诉你事实了, 这里用的是现在完成时, 表示过去的动作对现在造成了影响, 既然我已经说了, 我还必须重复一遍吗？4.A本题考查情态动词的用法。句意应为“我本来不应该看那部电影的-它会使我做噩梦的。”表示“本来不应该

44、做而做了某事”用shouldnt have done, 所以A项正确。5. A. 考查情态动词。迈克本来不必要那么忙的。这么高速驾驶之后，他早半个小时到达了。根据后面的语境，提前半个小时到达，说明Mark本来不必那么匆忙，所以用neednt have done 结构，表示“本来不必要做某事的而实际上做了”。6.B考查情态动词。表请求可用情态动词can, may, could, might ,表允许用can, may.句意为：“我可以将这本书带出去吗？”“恐怕不行”。故应选表情请求的情态动词may。7. A耐心一点儿，你不能期望世界变化如此快。通过选项此题考察情态动词，cant在否定句中可以表示推测，译为不可能，可以表示能力，译为不能够，也可以表示命令，不允许，但是语气比mustnt弱，具有劝慰的意思，根据句意此题中选择A，cant表示劝慰。8. B，shall在第二人称中表示允诺，还可以表示强制，命