高中英语必修三情态动词（unit 1 ，unit 2）一、情态动词的特点:1.没有人称和数的变化。
2. 有些情态动词有过去式的变化:e.g. will → would , can → could , may→ might ,dare → dared二、情态动词的否定式:情态动词+ not +动词原形can not: can't , must not: mustn't , need not : needn't三、情态动词的用法及相互区别, 是考试的内容之一1. can , be able to be able to 表示经过努力后, 能够做到; be able to 有多种形式的变化。
can1). 表示体力或脑力方面的能力;2). 表示允许、可能性。
could 是can的过去式, 表示过去有能力及过去存在的可能性; 用于疑问句表示委婉地提出问题。
1) The fire spread through the hotel very quickly but everyone ____ get out. (NMET 97 )A. had toB. wouldC. couldD. was able to2) -Will you stay for lunch?-Sorry, __. My brother is coming to see me. (NMET99)A. I mustn'tB. I can'tC. I needn'tD. I won't2.may 表示询问或说明一件事可不可做; 表示某事有可能发生。
might是may的过去式; 用在疑问中比may委婉、客气。
1) -May I take this book out of the reading-room?-No, you mustn't. ( Yes, you may.)2) -Might I make a suggestion? -Yes, you may.3. must1). 表示必须要做的事: 必须2) 表示很有把握的推断: 一定, 准是。
have (has)to : have (has)got to 必须, 不得不。
过去式: had to3) -Must I get to the station before three o'clock?-Yes, you must. ( No, you needn't. )4) I'm afraid you will have to wait a while.5) She must be in the classroom now.6) Mary ____ be in Paris, I saw her in town only a few minutes ago. (NMET 94)A. mustn'tB. shouldn'tC. can'tD. may not4. shall1) 在疑问句中, 用于第一、三人称表示说话人征求对方的意见或向对方请求。
2) 用于二、三人称,表示说话人给对方的命令、警告、允诺等概念。
1) - Shall I place an order with you now? -No, you needn’t.-Shall he turn down the radio a bit? -Yes, please.(No, please don't.)2) You shall have the English book as soon as I finish it.3) Everything that he owns shall be taken away from him.4) Your brother seldom comes to see you, ____?A. does heB. doesn't heC. will heD. isn't he5) It's a fine day. Let's go fishing, ____?A. won't weB. will weC. don't weD. shall we5. should 应该; 应当1) You should listen to the doctor's advice.2) You should study the article carefully.6. will, would1) 在疑问句中用于第二人称,表示说话人向对方提出请求或询问。
用would语气更加婉转。
2) will 表示现在的习惯性动作或状态; would 表示过去的习惯性动作或状态。
3) will 用于各种人称, 表示意志、意愿、决心、允诺; would 表示过去时间的意志、意愿、......。
(1) Don't smoke in the meeting room, ___ you?A. do youB. will youC. can youD. could you-Will you come with me? -Yes, I will.(I am sorry , I can't.)(2) -Would you tell us something about yourself? -Yes, I will.(3) - It's my birthday tomorrow. Don't forget to come to my party.- _____ .A. I don'tB. I won'tC. I can'tD. I haven'7. ought to 应该; 应当1) You oughtn't to smoke too much.2) She ____ for what she has done.A. ought to praiseB. ought be praisedC. ought to have praisedD. ought to be praise8. dare 1. dare to come 2. dare come1) He dare not tell the truth.2) He doesn't dare to come out at night.3) I don't know whether he ____ try.A. dareB. needsC. wantsD. is allowed9. need1). 作为情态动词:必须2). 作为实义动词: 需要A.主语是人need( to do something ; to be done by somebody)B. 主语是事物need ( doing; to be done)1) -Do they need to take any books with them?-No, they don't need to.2) -Need we buy any new equipment? -No, we needn't.3) This farm tool needs repairing.This farm tool needs to be repaired.4) -Shall I tell John about it ?- No, you ___ . I've told him already.A. needn'tB. wouldn'tC. mustn'tD. shouldn't5) It's a fine day. You ____ take a raincoat with you.A. can'tB. mustn'tC. needn'tD. may not情态动词+ 不定式的完成式是高考的考试要点1、must have done,“一定做过/一定已经．．．”，表示对过去情况极大把握地推测，仅用于肯定句2、may/might have done 也许做过某事（推测）；本来可以做某事却没做3、can't have done 为否定句或疑问句,对过去的推测“不可能，一定没做过某事”could have done本来可以做某事却没做4. needn’t have done 表示”不必要做某事，但做了”，而needn’t do 则表示”不必做(也没做)”5.、ought to /should have done 表示”本来应当做的却没做”oughtn’t / shouldn’t have done 本来不应该做某事却做了6、would/could/might/should + have done 用来表示与过去事实相反的虚拟语气7、would rather have done 表示”当时宁愿做了某事”，否定形式：would rather not have donee.g. If I had been free that day, I would have gone with you.8、would like/love to have done 表示” 本想做某事” 而实际上未做。