专转本英语语法-情态动词

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1、三、情态动词The usages of modal verbs（Fill in the chart after reading the materials.） model verbsBasic Chinese meaningusagesExamples1Can（could）（5种用法）“能”，“会”1）表能力Both of them can swim.注 1 can 和be able to 同义，但can只用于现在式和过去式(could)。be able to可以用于各种时态。They will be able to tell you the news soon. 他很快就能告诉你消息了。注2

2、：was（were） able + 不定式不仅表示过去能做某事，而且一般都是成功行为（表成功地做了某事），这时不能用could 替换，不过在否定句中二者可以互换。1 . He didnt agree with me at first but I was able to persuade him.他起初不同意但我能说服他。 2. He was able to flee Europe before the war broke out.= He managed to flee Europe before the war broke out.3 . He wasnt able to （or could

3、nt） see me before I left.我离开之前他不能再见到我了。2）提出委婉的请求 may，（注意在回答中不可用could），此时could和can没有时间上的差别，could 更委婉。- Could/Can I have the television on? - Yes, you can. / No, you cant.3）can和could用在否定句，疑问句中用来表示推测或怀疑。can较could更加表示说话人肯定的语气。注 can不能用在肯定句中表示推测，它在肯定句中只表示能力。例如，只能说“He may be at home（他可能在家）”，不能说“He can be a

4、t home”。（1）can/coulddo （对现在情况的推测）He cant be at work. 他不可能在上班。 Can what he said be true? 他说的话靠得住吗？ （2）can/couldbe doing表示对目前正在进行行为的猜测。例 1 They cannot be cleaning the room at the moment. 他们现在不可能在打扫房间。例 2 What could they be doing yesterday afternoon? 昨天下午他们可能在做什么呢？（3） can/could have done，都可表示对过去某事物的猜测，

5、can 只能用于疑问句和否定句中，而could既可以用于肯定句，也可用于否定句和疑问句中，could + 完成时动词还可表示事实上没有实现的行为，带有责备的含义。例 1 You couldnt have seen him yesterday because he was out of the town. 你不可能在昨天见到他，因为他出城了。例 2 Can he have done the experiment? 他会做完实验了吗？ 例 3 John cant have forgotten my name. 约翰不可能忘了我的名字。例 4 He could have come earlier.他

6、可以早一点儿来。4）could 用在wish后的宾语从句或虚拟条件句中I wish I could sleep all day. 我希望能睡一整天。If my family were rich，I could have bought the car. 如果以前我家富有，我已买车了。5）cannot （或 couldnt ）和too连用表示“也不过分”意We can not recommend this book too strongly. 这本书我们无论怎样推荐都不过分。I cannot see you too often. 我和你见面次数越多越好。2may（might）(四种用法) “可以”

7、1） 表示允许或请求 can/could May I use your pen ?(Yes, you may. No, you mustnt.)2）表示没有把握的推测（用于肯定句或否定句）；（注意： might 表示推测时，不表示时态。只是可能性比may 小。）(注意：may be 与 maybe)（1）may/mightdo （对现在情况的推测）He might be at home.He may not be at home.Peter may come with us tonight, but he isnt very sure yet.(2)may/mightbe doing表示对目前

8、正在进行行为的猜测。He may be writing a book.（3）may/might have done，表示对过去情况的猜测You may have read some account(报道，叙述) of the matter.3）may 放在句首，表示祝愿。May God bless you!4） 用于短语： may/might as well 加动词原形，意为不妨。If that is the case(如果情况那样), we may as well try.3must（2大用法， 1比较）“必须”“想必、 一定”1) must表示必须，否定回答时用neednt. mustnt

9、表示不许可。You must get to the station before 3, otherwise you will miss the train. Must I hand in my homework tomorrow?No, you neednt. You can turn it in the day after tomorrow. You mustnt smoke in the hospital.2) 表推测Must只用于肯定句中表推测，意为一定或“想必”。（1）mustdo （对现在情况的推测）She must live near here, for she comes to

10、work on foot.He must be in the bedroom.You have worked hard all day. You must be tired. 你辛苦干一整天，一定累了。(2)mustbe doing表示对目前正在进行行为的猜测。He must be working in his office. He must be staying there.他现在肯定呆在那里。（3）must have done，表示对过去情况的猜测。对过去的推测是考试的重点。She was absent from class. There must have been something

11、wrong with her.The light was out. They must have gone to bed.I didnt hear the phone. I must have been asleep.我刚才没有听到电话，我想必是睡着了。（4） must have been doing（must 后接完成进行式）表示对过去某时正发生的事情的推测。-Why didnt you answer my phone call?-Well, I must have been sleeping, so I didnt hear it. 3)比较have to和must（1）两词都是必须的意思

12、，have to 表示客观的需要， must 表示说话人主观上的看法，或主观上的必要。My brother was very ill, so I had to call the doctor in the middle of the night.我弟弟病得很厉害，我只得半夜里把医生请来。(客观上需要做这件事)He said that they must work hard. 他说他们必须努力工作。（主观上要做这件事） 2)have to有人称、数、时态的变化，而must只有一种形式。但must 可用于间接引语中表示过去的必要或义务。He had to look after his sister

13、 yesterday.注： 在否定结构中： dont have to 表示不必mustnt表示禁止， You dont have to tell him about it. 你不一定要把此事告诉他。You mustnt tell him about it.你一定不要把这件事告诉他。4need dare(4点注意事项)这两词既可做实义动词用，又可做情态动词用。Need表示“需要”，dare 表示“敢”的意思。1) 情态动词： need、dare作为情态动词，没有过去的形态，两者都只能用于疑问句，否定句和条件句。2） need 和 dare 后用完成时用在否定句中，表示本来不必做而实际上已经做的事

14、。Need you go yet? Yes, I must. / No, I neednt.He said we neednt take all facts into account. 他说我们无需将所有的因素考虑进去。He dare not ask you, because he thought he must be wrong. 他不敢问你，因为他认为他准错了。例 1 You neednt have worried about your health; the doctor will care for you. 你其实不必担心你的健康，医生会照顾好你的。例 2 I dare not hav

15、e expressed my viewpoint. 我本来不敢阐述我的观点。3）need 用作实义动词：（1）need （需要, 要求）+ n. / to do sth例 1 He needs to try one more experiment. 他需要再做一次实验。例 2 He told me that his proposal needed to be taken into consideration.他告诉我务必考虑他的建议。（2）need, want, require, worth（形容词）后面接doing可以表示被动含义：且need/want/ require doing = ne

16、ed/want/ require to be doneThe bike needs/wants/ requires repairing.= The bike needs/wants/ requires to be repaired.The book is worth reading.4）need与have to 用法辨析need表示需要，主要用于否定句和疑问句。用于疑问句，肯定回答用must，否定回答用neednt。have to表示他人或客观情况要求“必须”，也可以翻译为“不得不”，have to否定形式意思是“不一定”或“没有必要”。You neednt come if you dont

17、want to.I dont think you need be so polite to her.You dont have to work so hard if you just want to pass Band 4.Because of the heavy rain, the children have had to get up earlier than usual this week.5shall(3点注意事项)1）shall用于第二、三人称，表示许诺、答应、命令等。If he passes the exam he shall have a holiday.The law shal

18、l comes into effect on May 1st. 2）shall用于第一人称，表示向对方征求意见Shall we leave now？ Shall I go home ?注：shall （助动词）还可构成一般将来时，用于第一人称，I / We shall -= I / We will -.6Should(be supposed to) 和ought to（2点用法）“应该”（1） should和ought to表示责任、建议或劝告，翻译为“应该”，ought to语气强一些。强调客观情况和在规定义务上应做的事，否定形式为ought not to 表示“不许可”。You shoul

19、d listen to the doctors advice if you want to recover soon.Such things ought not to be allowed.-Ought he to go?-Yes. I think he ought to. The teacher is supposed to give us a grade at the end of the semester. She ought to look after her children better.她应该更好地照顾孩子。Anyone who breaks the law ought to b

20、e punished. 任何违法的人都应该受到惩罚。You ought not to go on living this way. 你不可这样生活下去。（2）shouldhave done，是一种谴责，表示过去应该做而没有做或过去做了而不应该做。ought tohave done，用在肯定句中，表示过去该做而实际上未做的事，含有责备的语气。 I missed the class. I should have come earlier.I shouldnt have made such a foolish mistake. He ought to have criticized the boy.

21、 他应该批评这个男孩。 The building ought to have finished last month.这座大楼上月就该交工了。7will与would1) will作情态动词，表示意愿、习惯等。would表示过去的习惯。It will be highly appreciated if you will send us your latest price list.On Sundays he would get up early and go fishing.2) 2）Will/would you please do.,Would you like to do.,Would you

22、 mind doing.都表示建议、询问、请求等。Will you please pass me a cup of tea?Would you like me to give you a hand?This box is too heavy, would you please give me a hand? will用于祈使句的反意疑问句中（可认为will 是助动词）Come earlier next time, will you?（表请求，建议、询问）Do sit down，wont you？（用来提出邀请）注意：Let us sing an English song， will you？L

23、ets sing an English song， shallWe？3) will既可当作情态动词，表请求、建议、也可作为实义动词表意愿、意志、决心。3）-Dont forget to come to my birthday party tomorrow. -_.A. I dont B.I wont C. I cantD. I havent答案B. 本题表示决心.注意： （1）Will you?Would you like? 表示肯定含义的请求劝说时，疑问句中一般用some, 而不是any。Would you like some cake?（2）否定结构中用will，一般不用would, wo

24、nt you是一种委婉语气。Wont you sit down?8had better最好had better 相当于一个助动词，它只有一种形式，它后面要跟动词原形。had better do sth； had better not do sthIt is pretty cold. Youd better put on my coat.Shed better not play with the dog. had better have done sth表示与事实相反的结果，意为本来最好。You had better have come earlier.9would rather宁愿would

25、rather do would rather not dowould rather than 宁愿而不愿。还有would/had sooner, had rather都表示宁愿、宁可的意思。c.f no sooner than = hardly/barely/scarcely when(主句用过去完成时，从句用一般过去时)“一就”He had no sooner locked the door than his mother called him. If I have a choice, I had sooner not continue my studies at this school.I

26、 would rather stay here than go home. = I would stay here rather than go home.10used to“过去常常干”“used to do”表示过去常常干某事，现在不再干了。否定式为：used not to do/ didnt useto do注意： （1）used to与would表“过去常常”的区别（见7 will/ would的用法）（2）cfI used to go to work by bus. Now I take a taxi. She used to be very shy. “be/get/become

27、used to doing”表示习惯于干某事。 I am used to getting up early and going to bed early.He is used to being praised by others.be used to do （use的被动语态）“被用来做”The bricks will be used to build theAdministration building. Conclusion of some points 1几个情态动词开头的一般疑问句的回答方式 问句 肯定回答 否定回答Must sb.?Yes，sb. Must. No, sb. Need

28、nt.May sb.? Yes，sb. may. No, sb. mustnt.Need sb.? Yes，sb. must. No, sb. neednt/dont have to. 2.情态动词表推测考点情态动词具有自己的词汇意义，其基本用法为“情态动词动词原形”构成谓语，其中动词原形通常为一般式。Time is up. We must leave now. 时间到了，我们必须离开了。 You shouldnt be so careless. 你不该这么粗心。 情态动词的推测性用法与非推测性用法 1当情态动词指客观事实或现实时，是非推测性的用法 2当情态动词指说话人的看法、设想或猜测时，是

29、推测性用法 大多数情态动词均有上述两种用法，使用时应尤其注意其推测性用法，推测性用法的四种结构：情态动词+be十表语。表示对现在情况的推测，意为“应当一定可能” If he is not at the office, he must be somewhere. 他不在办公室，一定在其他什么地方。 They should be back by now. 他们现在应该回来了。情态动词+动词进行时，表示对正在进行的情况的推测。意为“应当一定可能正在 It must be raining outside. 外面一定在下雨。 Mary cant be telling the truth. 玛莉不可能在说

30、真话。 情态动词+动词完成时，表示对过去某种行为的推测，意为“应当想必可能已经 You must have got the letter. 你一定收到那封信了。 You couldnt have seen him because he has gone abroad with his parents. 你不可能看到他，因为他已经跟他的父母出国了。情态动词+动词的现在完成进行时。表示对过去正在发生事情的推测。Your mother must have been looking for you.你妈妈一定一直在找你。 They are sweating all over. They must ha

31、ve been working in the fields.They may have been discussing the problem this morning.She couldnt have been swimming all day. 在附加疑问句中，musthave过去分词结构的操作词一般应视具体语境用must后动词的适当形式来表示。例如：He must have waited here for a long time, hasnt he? 他一定在这里等了很长时间，是吗？(该句的意思是：Im sure he has waited here for a long time.)

32、You must have seen the film last night, didnt you? 你昨天晚上一定看了电影，对吗？(该句的意思是：Im sure you saw the film last night.) You must have been abroad, havent you? 你一定去过国外，对吗？(该句的意思是：Im sure you have been abroad.) You must have been abroad several years ago, werent you? 你几年前一定去过国外，是吗？(该句的意思是：Im sure you were abroad several years ago.)