情态动词归纳性讲解

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1、情态动词I.种类：1）只能作情态动词:can, must, ought to, may 2) 既能情又助：will, shall, would, should 3) 既情又行为：need, dare 4) 短语：be able to, have to, used to, had better, would ratherII.用法：1.表猜测，可能性： must, may, might, can, could 1)must表肯定 “猜测”(指说话人看来一定是，必然是)只能用在肯定句中： It must be headmaster. Your father must be nearly forty

2、 now.还可以用 must be doingHe must be enjoying himself.当must表推测是，否定不用 must not, 而用 cannotIt cant be headmaster. 表必须，一定 ：（肯定用must,否定用 mustnt 一定不要，表禁止） You mustnt smoke here. 2)may, can 表可能在肯定句中may表示事实上的可能性，（某事将发生的实际可能性。）can 表示逻辑上的可能性： 比较：The road may be blocked.(=It is possible that the road is blocked.=

3、Perhaps the road is blocked.)由于某种原因路可能被阻塞了。 The road can be blocked.(= It is possible for the road to be blocked.= It is possible to block the road.根据逻辑推理表示可能会出现某种情况，并不牵涉具体的事情是否会发生。 Accidents can happen on such a rainy day. 比较：Mr. Li looks pale. He may be ill.(事实上的可能性) Mr. Li is in poor health. He c

4、an be ill at any time. （逻辑上的可能性） 在否定和疑问句中，便不存在这种“事实上的可能性” 和“逻辑上的可能性”的区别，因为在否定句和疑问句中，通常是用can而不是用may表示可能。We may go camping next Sunday. （事实）Will you answer the doorbell? It may be your father.This may/ might/ could be done by him.Can it be true?What can he be thinking of? 3)can, could （一般用于疑问和否定句或感叹句中

5、表惊异，怀疑，不相信的推测 ）可能，能够 This cant be done by him. This may not be done by him.(弱) Can this be done by him? How can he so rude to others? He cant be more than thirty. 5）情态动词加原形表对一般情况的猜测，但would, could, might并不一定与过去时间有关，而表示可能性弱于它们相应的现在时形式。 He may/ might be a student. He cant / couldnt be a student. 6) 时态：

6、 can, may, mustcan/ may/ must +do对现在或将来的动作进行推测can/ may/ must + be doing是对眼下正在进行的动作进行推测can/ may/ must + have done是推测过去时间可能发生的事情 must/ may/might have done (肯定) cant / couldnt have done (否定) could/ canhave done (疑问) They may have settled the problem. I might have come to a wrong conclusion. The road is

7、nt wet. It cant have rained last night. Could Mary have missed the first bus? She got up very early. 7) 反意问句：情态动词表推测，不用情态动词反问，具体根据后面的时态而定： It must have rained last night, didnt it? He must have told you about it, hasnt he? 8) should 推断的“应该会” 不是责任义务的应该 -When will I get this photos? -They should be re

8、ady by 12 oclock. Its 12 oclock. He should come back at any moment. Should= ought to 应该 Should / ought to have done 本应该 Should 还可译成“竟然” You cant imagine that a well-behaved gentleman _ be so rude to a lady. A. might B. need C. should D. would 【1】You _ be tired - youve been working for an hour. A. mu

9、st not B. wont C. cant D. may not 【2】-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. can 【3】You might just as well tell the manufacturer that male customs _ not like the design of the furniture. A. must B. shall C. may D. need

10、【4】-Isnt that Anns husband over there? -No, it _ be him-Im sure he doesnt wear glasses. A. cant B. mustnt C. wont D. may not 【5】-Who is the girl standing over there ? -Well, if you _ know, her mane id Mabel. A. may B. can C. must D. shall 【6】2.(表允许)可以 may, can , might 1) may 在陈述句中，may 表示“许可”，通常是指说话人

11、给予的许可，口语中可以用 can 例： You may / can smoke in this room. =You are permitted (by me) to You may / can come if you wish. 否定用may not 表示说话人不许可，例： You may not go. （= I dont permit you to.） May not 也可表示一般的不许可，即表示根据一般规定而不是说话人不许可：例： Borrowers may not take out of the library more than two books at a time. Can可以

12、用来表示普遍的许可，即不指明是谁给予的许可: You can keep the book for more than two weeks. May 在疑问句或if 从句中,may 不是说话人给予的许可，而是征询听话人的许可，例： May I 征询对方许可比较正式，在口气上比较客气，在口语中用 Can I ? May / Can I smoke in this room? (= Will you allow me to)May I go now? 再问客观上是否允许时用can时更多一些，如： Can we take the books out of the room? 2) might, cou

13、ld, would 表请求许可时,不表过去，只是语气更加委婉，客气。 Might I have a look at your new dictionary? -Could / might I use your bike tomorrow morning? -Yes, you can/ may. No, Im afraid not. 不能用：Yes, you could/ might. 3）shall在疑问句中用于一，三人称表征询听话人的意见或意图，如：Shall I carry your suitcase? (=Do you want me to carry your suitcase? Sh

14、all we have dinner? (=Do you agree to our having dinner now) Where shall I wait for you? Shall we sit here? Shall he come to see you? 要不要他来看你？4）will在疑问句中用于第二人称,表示请求（请对方做某事）would 更加委婉 Will you help me with my English? Will you sing at the concert tomorrow evening? Would you tell me the way to the sta

15、tion? 必须用would 的场合 Would you like/prefer/ love to go with me? Would /Do you mind if I open the door?3. 表能力：can 和 be able to 都表能力 1) be able to 主语必须是人或动物，而can没有这个限制。 He can swim. = He is able to swim. The radio can be fixed in 30 minutes.(不能用 be able to) 2)be able to 可以有任何形式，而can只有过去式could He will be

16、 able to skate as well as you. The foreigners come to China without being able to speak Chinese. 3)be able to 的过去式（was/were able to）可作“设法做成某事讲相当于manage to do 或 succeed in doing With the help of the firemen, they were able to leave the burning house.(were able to 不能换成could.) 4. 表必须 must, have to, sha

17、ll must说话人的主观意志，或要求某人必须做某事. have to 表客观需要 例： I must go now, or Ill be late.shall用于二，三人称表允诺，警告，命令，决心，强制 Dont worry. You shall get the answer this afternoon.(允诺) He shall be sorry for it one day. (警告) Nothing shall stop us from coming.(决心)5.will, would 1）表意愿（用于陈述句，可用于各种人称,有时态变化） I will stop smoking. -

18、Give my regards to your family. -Of course, I will. I wished him to give up smoking, but he wouldnt listen. 2）表功能，有时态变化 The door wont open. My radio wont work.6.表习惯性动作：will, would ; used to“总是” “惯于” I will sit here for several hours. would / used to When I was a child, I would / used to get up early

19、 and go fishing. There used to a river in the village. (不能用would)7.回答问句时有变化的情态动词： 1)Must we hand in our homework today? -Yes, you must. No, you neednt. you dont have to 2)-May I take this book out of the reading-room? -Yes, you may. No, you mustnt. you may not. youd better not. 3) -Need you go now?

20、-Yes, I must. -No, you neednt. 4) Could you explain it to me? Yes, I will.(愿意) Could I use your book? Yes, you can. (不用could) 5) Shall I tell him about it? No, you neednt. I have told him. Shall I invite him to go with us? No, you mustnt. I dont want to see him again. 6) Would you mind opening the d

21、oor? No, indeed. (Of course not./ Certainly not. / Not at all.) 若Would you mind my opening the door? No, go ahead.7. need; dare He doesnt dare ( to) answer. Does he dare to go? Dont you dare ( to) touch it?8.情态动词 + have done 1) should have done 本应该 ought to have done shouldnt have done You should ha

22、ve handed in your home work on time. -Mary looks sad. Did you tell her about the accident. -Yes, but I should have told her later. 2)neednt have done 本不必做的事做了（无肯定式） neednt do 不必做（没做） L1.She neednt have hurried. There was much time left. L2.She neednt hurry. There is much time left. L3.-I forgot to b

23、ring the dictionary here. L4.-You didnt need to bring it here. Because we havent allowed to use it. L5.-I dont mind telling you what I know. -You _. Im not asking you for it. A. mustnt B. may not C. cant D. neednt 3) must have done He must have told you about it. cant have done may/ might have done 4) could have done 本能做（没做） 5) would like to have done Would like to do 6) would rather have done Would rather do -Did you criticize him for his mistakes? -Yes, but I would rather not have done9表祝愿：may May you succeed!6