情态动词和虚拟语气详解.doc

情态动词和虚拟语气 【考点分析】情态动词1.考查情态动词的基本用法shall用于一、三人称疑问句表示征求对方意见;用于二、三人称陈述句表示说话人给对方的命令、警告、允诺或威胁等;may表示“允许、可以”，语气比较委婉。must用于疑问句，表示责备、抱怨的感情色彩，意思为“偏偏，偏要”，mustnt表示禁止，是说话人强有力的劝告。cannot 表示“不可能”;need not 表示“不必要”;may not 表示“可能不，可以不”。neednt表示“没有必要”would表示过去反复发生的动作或某种倾向表示经过努力而成功的某一次动作，只能用was/were able to,而不能用could;could还可以表示过去的某种能力考查情态动词用作答语的情况2.考查情态动词+动词不定式一般式表推测的用法肯定的推测一般用must,should,may(might)或could(不用can)，其中，must的语气最强，译为“肯定”、should的语气次之，译为“很可能”、“应该”;按常理推测的may(might),could语气最弱，译为“也许”。否定的推测：语气不很肯定时，常用may not,might not或could not，译为“可能不”“也许不”;否定语气较强时，则用cant，译为“根本不可能”、“想必不会”，表示惊异、怀疑的感情色彩疑问句中推测往往用can或could3.考查情态动词+动词不定式的完成式表推测的用法4.考查情态动词+动词不定式完成式的其他用法should(ought to)+不定式的完成式：本来应该做而实际上又没有做。其否定形式表示某中行为不该发生却发生了。neednt+不定式的完成式：本来不必要做的而实际上又做了could+不定式的完成式：本可以做而实际上未能做,含有遗憾的意味虚拟语气1.虚拟条件句的基本结构及其用法与现在事实相反的虚拟条件句与过去事实相反的虚拟条件句与将来事实相反的虚拟条件句2.虚拟语气的活用时间错综虚拟结构省略if的虚拟结构并列连词或副词暗示的虚拟结构介词或介词短语暗示的虚拟结构as if / as though方式状语从句中的虚拟语气名词性从句中的虚拟语气分词短语暗示的虚拟结构上下文语境中的虚拟结构【知识点归纳】I.情态动词1.表示“能力、许可”的can /may表示能力的情态动词用can/couldA computer_think for itself, it must be told what to do.A.cant B.couldnt C.may not D.might not表示许可时用may/might ,can/could 都可以，但在问句中用could?或might? 以使口气委婉客气，其回答一定要用can或may，以使回答口气明确(must表示一定，必须，mustnt表示禁止，不许可)Could I call you by your first name? Yes, you_A.will B.could C.may D.mightJohnny, you_play with the knife, you_hurt yourself.A. wont/cant B.mustnt/may C.shouldnt/must D.cant/shouldnt在肯定句中could不可以用来表示过去某一特定场合的能力，而要用was/were able to。如不可以说：They could jump into the sea before the boat was blown up而要说：they were able to/managed to jump intoThe fire spread through the hotel very quickly but everyone_get out.A.had to B.would C.could D.was able to但在否定句中could/was(were)able to可以通用:I couldnt/wasnt able to see him yeaterday.表示许可时用may/can都可以。只不过用may时较侧重讲话人的许可，而can较侧重客观情况的许可，must则表示必须做某事。2.表示“推断、判断”的can,may,must在肯定句中都可以用来表示可能。在含义上must语气最为肯定,may表示的是事实上的可能性：Peter_come with us tonight, but he isnt very sure yet.A.must B.may C.can D.will而can表示的是逻辑上的可能性：Mary is in poor health. She can be ill at any times.在否定句中只能用can和may。此时cant用以代替mustnt，语气比may not更强。cant中文可以翻译为“不可能”、may not中文可以翻译为“可能不”。Michael_be a policeman, for hes much too short.A.neednt B.cant C.should D.may在疑问句只能用can，不能用may和mustHe may be very busy now. Can he be very busy now?He must be very busy now. Can he be very busy now?3.表示“请求、提议”(用在疑问句中)的can和could，这时could比can语气更婉转Can(Could)you give me a lift to the station?你(您)能不能让我搭你(您)的车去车站呀?4.表示“惊讶、怀疑”(用在疑问句中)的can和could，这时could比can语气更婉转Who can it be at this time of day?这个时候到底会是谁呢?5.构成下列特殊句式的cancan not/can nevertoo cannotenough“无论怎么也不为过分，越越好，非常”Since it is a good thing,we cannot do it too soon.既然是好事情，我们越早开始做越好。cant help doing,cannot help but do,cannot but do“禁不住，不由得，不得不”I cannot help admiring the picture whenever I look at it.每当我看到这幅画时，我都禁不住要鉴赏它。When a close friend dies,you cannot but feel sad.亲密的朋友去世时，你会不由得感到悲伤。6.表示祝愿、祝福的may,此时句子用倒装语序May he live to an old age!愿他长命百岁!May God be with you!愿上帝保佑你!7.shall/should 用于人称 意义Shall 第一、三人称 征求对方的意见 第二、三人称 说话人给对方的警告、命令、允诺、威胁 用于法律、法规等条文中 应，须，得What shall we do this evening?注意：may用于征求对方的许可，而shall用于征求对方的意见或指示：May I have a look?我能看一看吗?Shall I have a look?需要我看一看吗?You shall fail if you dont work harder. (警告)He shall have the book when I finish reading. (允诺)He shall be punished.(威胁)The fine shall be given in cash.罚款须以现金缴纳。should 意义 （表义务、责任的）应该 （表预期的）应该会，想必会，一定会把 （表惊讶、遗憾的）竟然、居然 （与疑问词连用，表意外、惊讶、纳闷等的）究竟是，到底 （用于表示命令、建议、请求等词后面的that从句中，且should可以省略）应该，必须You should apologize to him.The photos should be ready by 12:00.Im surprised that you should speak in such a way.Who should ccome in but my old friend Betty.我当究竟是谁进来了呢，原来是我的老朋友贝蒂呀。I suggested that he (should)change his mind.My suggestion was that he (should)change his mind.注意：ought to表示 “应该” (与should同义, 只是语气稍重一些), 也可表示推测。You ought to take care of him.He ought to be home by now.8.will/would请求、建议，would比will委婉客气Would you pass me the book?表示意志、愿望和决心I will never do that again.They asked us if we would do that again可表示过去反复发生的动作或某种倾向During the vacation he would visit me every weekThe wound would not heal.表示估计或猜想It would be about ten when he left home.What would she be doing there?9.dare和needneed作为情态动词只有一种形式，只用于否定句和疑问句。dare作为情态动词用时有两中形式：dare和dared两个词形。除了可以用于否定句和疑问句外，还可以用于条件从句或表示怀疑的句子中。If he dare come,I will kick him out.I dont know whether he dare say.Note:He doesnt dare(to)answer the question.Does she dare(to)enter the dark room?10.情态动词+have done的用法could+have done：本可以做而实际上未能做You could have done better, but you didnt try your best.cannot+have done：表示对过去行为的否定推测He cannot have been to that town.can+主语+have done：表示对过去行为的怀疑或不肯定Can he have got the book?might(may)+ have done：对过去发生的行为不太肯定的推测He may not have finished the work.If we had taken the other road, we might have arrived earlier.(Mood:might>may,possibility:might<MAY)< p> must+have done：对过去发生的行为肯定的推测。其否定式为：cannot have doneYou must have seen the film.You cannot have seen the film.neednt+have done：本来不必要做的而实际上又做了You neednt have watered the flowers,for it is going to rain.注意：didnt need to(have to)do :没有必要做而实际上也没有做I didnt need to clean the windows.My sister did it 2 hours ago.should(ought to)+ have done：本来应该做而实际上又没有做。其否定形式表示某种行为不该发生却发生了。You should have started earlier, but you didnt.She shouldnt have taken away my measuring tape, for I wanted to use it.注意：本结构还可以表“推测”的意思He should have finished the work by now.到现在他应该已经做完那项工作了。11.其它情态动词have tohave to表示 “必须, 不得不”, 在这个意义上与must很接近, 但must表示的是说话人的主观看法, 而have to表示的却是客观需要. have to比must有更多的形式。The TV set is broken. I have to buy a new one.The students will have to know how to use the computers.注意：在回答must的问句时, 否定式常用need not(neednt)或dont have to表示 “不必”。而不用must not, 因为must not表示 “不可以”。used to表示过去的习惯动作或状态(现在已不复如此)Did you use to go there to see your brother? /Used you to go there to see your brother?Yes, I did(used to). /No , I didnt (usednt).注意：would也可表示过去反复发生的动作或某种倾向，但是不涉及到现在。had better表示 “最好(做)”We had better go now.其否定式为had better notII.虚拟语气(一)一般虚拟结构类别 用法 例句If引导的条件从句 与现在事实相反 从句动词：过去式（be用were）主句动词：should/would/could/might+动词原形 If he were here, he would help us. 与过去事实相反 从句动词：had+过去分词主句动词：should/would/could/might+have+过去分词 If I had been free, I would have visited you. 与将来事实相反 从句动词：过去式 / should+动词原形 / were+不定式主句动词：should/would/could/might+动词原形 If it should rain tomorrow, we would not go camping.注意:主句中的should只用于I、we，但在美国英语中，should常被would代替;从句中的should可用于各种人称，且不可以被would所代替。(二)混合虚拟结构1.不同时间的虚拟If he had listened to me, he would not be in trouble now.(从句与过去事实相反，主句与现在事实相反)If he had told me yesterday, I should know what to do now. (从句与过去事实相反，主句与现在事实相反)If I were you, I would have gone to her birthday party. (从句与现在事实相反，主句与过去事实相反)If you hadnt lent me some money, I couldnt have bought the new house and most likely I would be still living in the dangerous house now. (从句与过去事实相反，and后面的主句与现在事实相反)2.虚拟与陈述的混合He could have passed the exam, but he wasnt careful enough.You should have come earlier. The bus left a moment ago.(三)特殊句式虚拟结构1.省略连词if。在书面语中，如果虚拟条件从句中有were，had 或 should，可以把if省略，把这几个词放到主语之前，构成主谓倒装。Should he come (If he should come), tell him to ring me up. 他要是来了，让他给我打个电话。Were I you (If I were you), I would not do it. 我要是你，就不做这事。2.suggest, order, propose, request, require, commnd,demand, advise, insist+ 宾语从句(should )doHe suggested that we (should) save money for the future.The undergraduate insisted that he (should) go to work in the south.注意：当suggest表示暗示，insist表示坚持观点,事实时，后接的宾语从句应当用真实语气。His silence suggested that he agreed with my decision.He insists that doing morning exercises does good to peoples health.3.It is suggested/advised/ordered/requested/required+ that从句(should) doIt is proposed that more students should go to university.4.My advice/suggestion/request/requirement/order/proposal+ is +表语从句(should)doMy advice is that you should practise speaking English as often as possible.The order from the commander was that the troops should set off for the front immediately.5.His suggestion/advice/request/requirement+ 同位语从句(should )do+ is.The request that they should get more is reasonable.6.It is natural/necessary/strange/pity /important+that从句 (should) do表惊奇、怀疑、惋惜、不满、理应如此等。Its strange that he should have missed the train. (表竟然)It is important that we should learn from others.(表理应如此)It is a pity that he should not go with us.(表惊讶、不满)7.wish + that clause (did/were 与现在相反)wish + that clause (would/could/might + do与将来相反)wish + that clause ( had done 与过去相反)I wish I could go with them tomorrow.I wish I had never met him.8.It is (high/about) time + 从句(did或should do )It is (high/about) time we went home.9.would rather + that clause (did 与现在或将来相反);(had done 与过去相反)I would rather you came tomorrow.I would rather you hadnt told her the news.10.省去条件从句或主句：表示虚拟语气的主句或从句有时可以省略，但其含义仍可以推知。省去条件从句You could have washed your clothes yourself. 你本可以自已洗衣服的。省去了"If you had wanted to")(事实是:你自己没洗衣服，因为你不想洗。)省去主句(常用以表示愿望) If only + clause ( did/were与现在相反)/ (would/could/might + do与将来相反) /( had done 与过去相反) “要是.就好了“If my grandmother were with me! 如果我的祖母与我在一起多好啊!(事实是:祖母已不在世。)If only she had not left! 如果她没走就好了!(事实是:她已经走了。)If only he would come tomorrow!If only I had taken her advice!If only I were ten years younger!注意：only if是“只要”的意思，从句中用陈述语气。11.as if + clause (did/were 与现在相反) / (would/could/might + do与将来相反)/( had done 与过去相反)She treats Kate as if she were her own daughter.They talked as if they had been friends for years.12.would like/was/were to have done somethingI would like to have attended the party, but one of my friends came to see me.13.but for+名词But for your help we couldnt have succeeded in the experiment.14.注意虚拟条件从句的特殊形式Without electricity, human life would be quite different today.Without the air to hold some of the sun's heat, the earth at night would be freezing cold.15.注意转折语气连词引导的虚拟语气He hesitated for a moment before kicking the ball, otherwise he would have scored a goal.I told Sally how to get here, but perhaps I should have written it down for her.The captain kept calm in the terrible storm, otherwise the accident wouldn't have been prevented.Yesterday, Jane walked away from the discussion. Otherwise, she might have said something she would regret later.16.注意分词和独立结构引导的虚拟语气Given more than two hours, we could have done the work better.Not having finished the work, he couldn't have seen this film.【高考预测】1. Why didn't you tell me there was no meeting today? I _ all the way here _the heavy snow.A. needn't have driven;through B. can't have driven;acrossC. mustn't have driven;through D. shouldn't have driven;cross2. Mum, its none of my business. Why _ I care? Just because she is your sister.A. can B. should C. will D. may3. I didnt know you were good friends .You _.I have known her since she moved here. You were studying abroad then.A.may have B.neednt have C.couldnt have D.must have4. The concert was wonderful!Really? How I wish I _to the theatre with you yesterday!A. had gone B. might go C. were able to go D. would go5.The two strangers have been talking in the park for a long time as though they _old friends.A. are B. should be C. were D. would be6. _the heavy rain, we _the town.A. But for; should have reached B. Because of; would have reachedC. During the period of; we would reach D. In spite of; we should have reached7. If William _, he _that green peach.Luckily he was sent to the hospital in time.A. was warned; would not take B. had been warned; would not have takenC. would be warned; had not taken D. would have been warned; had not taken8. Is it good to look up every new word when I come across it in reading?No. You _because you are likely to guess the meaning from the context.A. cant B. mustnt C. dont have to D.ought not to9. _I use your computer to send an e-mail?Yes, you _. But you mustnt keep it too long.Ill surf the Internet after supper.A. Could; could B. Could; must C. Can; can D. Could; can10. When he lived there, he _go to that book shop at the corner with his girlfriend after work every day.A. would B. should C. had better D. might11. I hear youve got a set of Australian coins. _I have a look? Yes, certainly.A. Do B. May C.Shall D. Should12. What happened to the young trees we planted last week?The trees_well, but I didnt water them.A. might grow B. neednt have grown C. would grow D. would have grown13. What _ had Bob walked farther, as far as the river bank?A. would happen B.could happen C. would have happened D.neednt have happened14. Hurry up,Tom.Its high time we_ to the theater.A. will B. shall C. are going to D. went15. Do you think he will do me a favor? As far as I know, he is the last one to help others. He_be prepared to give you a hand, though.A. might B. must C. can D. should16. Even though Id hurt my leg, I_swim back to the river bank.A. could B. might C. had to D. was able to17. It is rather cold here. Shall we light a fire? No, we_because things are easy to catch fire.A. wont B. cant C. mustnt D. neednt18.Would you have told him the answer had it been possible?I would have, but I _so busy then.A. had been B. were C. was D. would be19. The young man insisted that he_ these watches and_free.A. stole, set B. had not stolen, be set C. steal, be set D. had stolen; must be set20. I _your address, otherwise I_you long before.A. had forgotten,had visited B.forgot, have visitedC. forgot,would have visited D.have forgotten,would visit21. I_you a beautiful present for your birthday,but I was short of money at that time.A. would buy B. had bought C. would like to have bought D. must have bought22.Do you feel like _ there or shall we take a bus?Id like to walk. But since there isn't much time left, I'd rather we_ a taxi.A. walki