]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:. 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 to<2) -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't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. must）1). 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 not[4. 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, ___ youA. 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 praise<8. 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 done. 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。