情态动词(07年版).ppt

1、情态动词,一、常见的功能： 1. 请求对方许可： Can/May/Could/Might I? （can多用于口语中，常用于第一人称表示请求允许做某事；could 较客气，may/might用于正式场合，语气较恭敬，might更客气。） 应答时用can或may,不用could或might. e.g. -Could I borrow your bike? -Yes, of course you can.,2. 表示可能性： (1) 询问是否有可能性 疑问句中常用can/could/might, 一般不用may e.g. Can/Could/Might it be a true story? 这会

2、是真实情况吗？ (2) 可能性的否定 may/might not表示某动作或状态可能不会发生或存在 cant/couldnt 表示某动作或状态不可能会发生或存在 e.g. He may/might not have enough money for a new car. 他可能没有足够的钱买新车。 He cant /couldnt have enough money for a new car. 他不可能有足够的钱买新车。,3. 询问是否必须做某事 常用句型：Must I ? / Need I ? （注意应答） e.g. -Must I wait until they come? -Yes,

3、you must. -No, you neednt. / No, you dont have to. / No, you dont neednt to. -Need we go over all the old lessons? -Yes, you must. 4.表示没有必要做某事 常用neednt, dont have to, dont need to表示 e.g. You neednt / dont have to / dont need to do that.,二、注意点： 1. can / could 的用法 (1) 表示能力 C.f: can/could与be able to 的区

4、别： A: can/could表示现在和过去的能力，而be able to用于更多的时态 B: 表示经过努力而成功地做成了某件具体的事情时，只能用was/were able to=managed to do =succeeded in doing e.g. The fire spread through the hotel very quickly, but everyone was able to get out.,(2) 表示许可：在疑问句中could比can语气更委婉。 e.g. Could you come a little earlier? (3) 表示可能性：用在疑问句和否定句中。

5、 e.g. Can she live here? It cant be true. (4) can可指一时的情况，译为“有时候会” e.g. He can be very friendly at times. Our house is on the top of the hill, and in winter the winds can be pretty cold. He is a bad-tempered fellow, but he can be quite charming when he wishes.,2. may/ might的用法 (1) 表示允许，may语气正式，侧重说话人的

6、许可。 e.g. You may take the book home. (2) 表示可能性，不用于疑问句。might 比may可能性小。 e.g. They may not be there today. (3) 表示祝愿、祝福。 e.g. May you succeed! May you be happy!,3. shall的用法： (1) shall用于第一、三人称疑问句中，表示说话人征求对方的意见或向对方请求 e.g. Shall we begin our class? When shall he be able to leave the hospital? (2) shall用于第二

7、、三人称的陈述句中，表示说话人的某种感情，如命令，警告，允诺，决心，威胁等。 e.g. You shall have a new bicycle on your birthday.(允诺) He shall have the book when I finish reading.(允诺),You shall fail if you dont work harder. (警告) If you will not obey me, you shall leave the house. 如果你不服从我，你必须离开这里。 If you children wont do as I tell you, yo

8、u shant go to the park.,4. should 的用法 (1) should用于含有surprising, amazing, shocked, sorry, ashamed等词的句子中，译为“居然，竟然”。 e.g. Im terribly sorry that they should think I did it on purpose. 我十分遗憾，他们居然认为我是故意做的。 若强调事情已发生，可用should have done e.g. I was shocked that she should have done such a thing like that. 她居

9、然做了那种事，我十分吃惊。,(2) should可表示说话者根据常理或常态对现在、将来或过去情况进行某种推测，可译为“可能，该” e.g. -When can I come for the photos? I need them tomorrow afternoon. -They _ be ready by 12:00. A. can B. should C. might D. need e.g. He should be taking a bath now. She has been studying hard. She should do well on the test tomorrow

10、. 她一直努力学习，明天的测验她应该考得好。 He should arrive at noon. 他该在中午到达。 They should have arrived at 8:30, but they didnt turn up. 他们本该在八点半到达，但他们并没有露面。,5. will 的用法 (1) 表示意志、愿望和决心(用于各种人称) e.g. I will never do that again. If you will listen, I will give you some advice. (if条件句中的will表示“愿意”而不是将 来时态) 不愿意用wont. e.g. If

11、they wont accept a cheque, well have to pay cash. (2) 谈论习惯和特性（would 表示过去的习惯行为或 特有的行为），含有“总是”，“习惯于”的意思。 e.g. He will arrive last and will be the first to leave. 他总是到得最后，走得最早。 Boys will be boys. Mr. Brown would go fishing on Sundays when he worked in that town.,(3) 表示一种倾向，一种不能控制的事，一种必然(普遍真理，自然倾向及事物品质)

12、 e.g. Man will die without water. 人没有水会死的。 (4) 物做主语时，will表示固有性质、功能，表示“因出毛病而不能”, 相当于There is something wrong with sth. 的含义。 e.g. The bus wont start. 汽车开不动了。 The door wont open. Oil and water wont mix.,6. must的用法 （1）表示主观必须，而have to表示客观不得不。 （2）表示推测，只用于肯定句，若要表示“不可能”， “一定不”用cant。 （3）表示“偏偏，硬要（做令人不快的事）” e.

13、g. The telephone must ring when I was busy in the kitchen. After I gave her my advice, she must go and do the opposite. Just when we were ready to go away for the holidays, the baby must catch a bad cold.,The car must break down just when we were about to start off. 我们正要出发时偏偏车坏了。 At a time when ever

14、ybody was in bed, he must turn his radio on. 大家都上床休息时他偏偏打开了收音机。,7. need & dare (1) 作情态动词时，要直接跟动词，直接提问，直接否 定；作行为动词时则没有这些特征 (2) 在否定句和疑问句中，need既可作情态动词又可 作行为动词；在否定句、疑问句和条件句中， dare 既可作情态动词又可作行为动词（常用作情 态动词）。 在肯定句中need和dare通常作行为动词。 (3) 作情态动词时，need没有过去式，而dare有过去 式，为dared. (4) 作行为动词时，在肯定句中，need 和dare后面 的动词是

15、带to 的不定式。在否定句和疑问句中， dare 后面的不定式可带to, 也可以省略to. e.g. He needs to work harder. They dare to swim across the river. He doesnt dare (to) answer.,7. 表示推测的情态动词 (1) 用于肯定推测的有：must(语气最强), may, might(语气最弱) 用于否定推测和疑问推测的有：cant, couldnt (2) 对现在情况的推测：情态动词+do 对正在进行的动作的推测：情态动词+be doing e.g. You must be waiting for s

16、omeone. 你 一定在等人吧。 (3) 对过去动作的推测：情态动词+have done,9. 情态动词+have done (1) must + have done 对过去情况的肯定推测，“肯定发生了某事”。 e.g. It must have rained last night. (2) should / ought to +have done 本该做而实 际上未做 e.g. You should have started earlier. Shouldnt/oughtnt to + have done 不该做而做了 e.g. You shouldnt have left without

17、 telling us. (3) may/might + have done 本可以做却没有做（表示惋惜） e.g. You might have passed the examination.,(4) could + have done A, 本能够做的却没有做，有委婉的责备语气 e.g. You could have come earlier. You could have been more considerate. B, 那时可能或不可能做某事 e.g. Nobody could have foreseen all this. 这一切是谁都预想不到的。 C, 那时“本来可以” e.g.

18、 You neednt have cooked it. We could have eaten it raw.,(5) neednt + have done 过去本不必做却做了 C.f: didnt need to do过去没有必要做因而也没做 e.g. Thank you for your gift, but you neednt have bought it, for I have already have enough. He got up very late yesterday, for it was Sunday and he didnt need to go to school.,10. 与情态动词有关的反意疑问句 (1) must表示“应该，必须”时，用must构成 e.g. We mu