精選優(yōu)質(zhì)文檔-傾情為你奉上情態(tài)動詞與虛擬語氣一、情態(tài)動詞考點一can和could的用法1表示驚訝，常用在否定句和疑問句中。How could you do such a silly thing?你怎么能做那樣的蠢事呢？2表示可能性，意為“可能，有時會”。can和could沒有時態(tài)的差異，只是could不太肯定。Jogging can be harmful to the health.慢跑可能會對健康有害Accidents can/could happen on such rainy days.這樣的多雨天氣可能會發(fā)生交通事故。(客觀的可能性)3can用于否定句，意為“應該不是，不可能”。I think it's all right. She can't make a mistake.我想應該沒事，她不可能犯錯誤。4cannot.too/enough表示“無論也不過分”；“越越好”。You can't be too careful while driving.開車時越小心越好。You cannot remember enough English words.你記的英語單詞越多越好。5cannot butdo sth.表示“不得不，只好”。I couldn't but choose to go. 我只好去。根據(jù)句意可知答案為B。考點二may和might的用法may和might表示“許可”，“可能性”，“祝愿”等意義。1表示許可。May I come in?Might I borrow your computer?2表示可能性。may和might表示可能性時，可以對現(xiàn)在、過去或?qū)磉M行推測。Peter may come with us tonight, but he isn't sure yet.彼得今晚可能和我們一起來，但他還沒確定。(實際可能性，不用can)3“may as well動詞原形”意為“最好，滿可以，倒不如”。You may as well do it at once.We may as well stay where we are.4may作“可以”講時，其否定式常用mustn't表示“禁止”；must作“必須”講時，其否定式是“needn't”，表示“不必”。May I use your car?No, you mustn't.(委婉的拒絕可用：Sorry，but I am using it now.或You'd better not.等)不，你不可以?？键c三must的用法1表示義務，意為“必須”(主觀意志)。We must do everything step by step.在這種用法中must表示出于主觀意識而必須要做某事，have to表示由于某種客觀原因而不得不做某事。除此以外，have to自身有時態(tài)的變化。I have to go now for I've got a meeting 15 minutes later.注意：回答以must引導的問句時，若是否定回答，不可以用mustn't而用needn't或是don't have to，因為mustn't意思是“絕不能，一定不要”，而沒有“不必”的意思。Must we hand in our exercises today?Yes, you must. 是的，必須交。(肯定回答)/No, you needn't (you don't have to)不，不必今天交。(否定回答)Must I work out the problem tonight?No, you needn't.2表示猜測、推測。must常用于肯定句中表示猜測。(對現(xiàn)在或未來的事進行猜測時，后接動詞原形；對已經(jīng)發(fā)生的事進行猜測時，后接have過去分詞。)He must be ill. He looks so pale.I didn't hear the phone. I must have been asleep.3表示禁止(用于否定句)。Smoking must not be allowed in the office.4表示“偏執(zhí)”，“固執(zhí)”。Must you make so much noise?If you must smoke, please go out.考點四shall的用法1第一、第三人稱疑問句中，表示說話人征求對方的意見和向?qū)Ψ秸埵?。Shall we begin our class? Shall the driver wait outside?2第二、第三人稱陳述句中，表說話人給對方的命令、警告、允諾或威脅。I promised he shall get a present for his birthday.You shall not get my support if you do such a thing.考點五will和would的用法1表示自愿做或主動提出做什么，如意志、愿望或決定等。would用于過去的情況。Can someone fetch some water?I will.2與you連用表示請求或要求：用won't you強調(diào)邀請的語氣。would比will更客氣、委婉。Would you mind opening the window for me?3will表示規(guī)律性的“注定會”。You will regret forever if you lose the chance.如果失去這個機會你會后悔一輩子的?？键c六need和dare的用法need和dare既可用作情態(tài)動詞，也可用作實義動詞。用作情態(tài)動詞時，主要用于否定句和疑問句。用作實義動詞時，可用于各種句式。1.做情態(tài)動詞You needn't telephone him now.She dare not go out alone at night.2用作實義動詞You don't need to do it yourself.The table needs painting (to be painted)We should dare to give our own opinion. He did not dare to look up.可知，空白處填Need。答句意為“還需要問嗎？當然是蒂姆了?！笨键c七used to和would1表示過去重復、習慣性動作時，used to可用would代替。He would sit at the door waiting for his son coming back.2used to強調(diào)過去與現(xiàn)在對比，would則沒這個意思。He used to get up early. 他以前常常起得很早。(他現(xiàn)在不早起了)3表示過去的狀態(tài)，只能用used to，不可以用would。There used to be a tree in my yard.考點八could/might/would/should表委婉的功能Could/Might I use your bike tomorrow morning?Yes, you can/may.(否定：No, I'm afraid not.) 好，你可以(用)。(不，恐怕不行。)不可說：Yes, you could/might.回答允許時，用could/might表委婉是不恰當?shù)?。Could I borrow your dictionary?Yes, of course you can.Would you do me a favor?考點九“情態(tài)動詞have done”的用法1must have done此結(jié)構(gòu)常用在肯定句中，表示對過去發(fā)生的行為的推測，意為“一定，肯定”。其否定或疑問形式用can't，而不用mustn't。He must have been drunk to say that. 他準是喝醉了才那樣說的。2shouldhave done表示本應該做而實際上沒有做，其否定式“shouldn't have done”表示某種行為不該發(fā)生卻發(fā)生了。I think he should have tried to get more qualifications before applying for the job. 我認為他在申請這份工作之前應首先努力取得更多的資格證明。3can (could)have done肯定式表示本來可以做而實際上未能做某事，疑問或否定形式表示對過去發(fā)生的行為懷疑或不肯定。You could have told me you were going to be late.4may (might)have done表示對過去(將來)發(fā)生的行為的推測，表示可能干了某事。Who knows what will happen? You may even have married by then.誰知道會發(fā)生什么呢？到那時你甚至可能已經(jīng)結(jié)婚了。5ought tohave done表示過去應做某事而實際未做，其否定式是“ought not to不定式完成式”，此時ought to可與should換用。What you ought to have done is call the police.6needn'thave done表示本來不必做某事而實際上做了某事。Terence has done so little work; he needn't have bothered to come to school today.特倫斯幾乎沒做什么功課，他今天其實就不用來學校。二、虛擬語氣考點一虛擬語氣用于狀語從句中1虛擬語氣用于非真實條件句條件從句主句例句與現(xiàn)在事實相反If I (we，you，he，she，it，they)動詞過去式(be的形式一律用were)I (we，you，he，she，it，they)would/should/could/might動詞原形If he were indoors, he wouldn't feel so cold.與過去事實相反If I (we，you，he，she，it，they) had過去分詞I (we，you，he，she，it，they)would/should/could/mighthave doneIf you had taken my advice, you wouldn't have failed in the examination.與將來事實相反A式：If主語一般過去時B式：If主語were to doC式：If主語should doI (we，do，he，she，it，they) would/should/could/might動詞原形A：If he were here this evening, we would play cards.B：If she were to marry Jack, she would be happy.C：If she should know it, she would tell me.2虛擬條件句和主句動作如發(fā)生的時間不一致，主句和從句的謂語要根據(jù)各自所指的不同時間選用適當?shù)奶摂M語氣形式，這種句子叫做錯綜時間條件句。If I were you, I wouldn't have missed the film last night.如果我是你，我就不會錯過昨晚那部電影了。(現(xiàn)在過去)If they had left home in early morning, they would arrive in half an hour.要是他們一大早離開家的話，再過半個小時就該到了。(過去將來)3蓄虛擬條件句，有時虛擬條件不用從句，而是通過上下文或用介詞短語等表示出來，常用的介詞有with，without，but for等。But for your help, we couldn't have succeeded.Without electricity life would be quite different today. 考題印證I _ to my cousin's birthday party last night, but I was not available.Awent Bhad gone Cwould go Dwould have gone考點二虛擬語氣用于名詞性從句中1用于賓語從句中。(1)wish后面所跟賓語從句中的虛擬語氣。表示對現(xiàn)在情況的虛擬：wish主語動詞過去式或were表示對過去情況的虛擬：wish主語had過去分詞表示對將來情況的虛擬：wish主語would/could動詞原形I wish (that) I were a bird and could fly freely in the sky.How I wish I had listened to my parents' advice!How I wish it weren't raining now. 考題印證Let's play football together tomorrow afternoon.OK, but how I wish I_ it as skillfully as you.Aplayed Bhave playedChad played Dwill play (2)用于表示建議、愿望、命令等詞后的賓語從句中，常見的動詞有：demand，order，require，insist，suggest，propose，advise等。賓語從句中的虛擬語氣結(jié)構(gòu)為“should動詞原形”，should可以省略。He suggested that we (should) start off early the next day. (3)在would rather后的賓語從句中，也用虛擬語氣，其結(jié)構(gòu)為：would rather sb.I would rather they didn't hear of the news.I would rather you hadn't told him the news yet.2用于主語從句中。It is desired/suggested/proposed/recommended/necessary/important/strange/natural/a pity/essentialthat從句，從句中的謂語動詞用“should動詞原形”，should可以省略。It is suggested that the meeting (should) be put off till next week.It is strange that he (should) have acted toward his parents like that.(act在主句謂語動詞be之前發(fā)生，所以要用“should have acted”)真奇怪他竟然那樣對他父母?？碱}印證It's strongly suggested that measures _ students to cheat in the exams.Abe taken to prevent Bbe taken to forbidCare taken to prevent Dare taken to forbid3用于表語從句和同位語從句中。在suggestion，proposal，order，plan，idea，request，advice等名詞后的表語從句和同位語從句中要用虛擬語氣，其構(gòu)成是“should動詞原形”，should可以省略。My idea is that we (should) think it over before accepting it.We all agreed to his suggestion that we (should) go to Dalian for sightseeing.4. 當insist表“堅持說，認為”、suggest 表“暗示，表明”、advice 表“通知，告知”這些特殊意思時，從句中不用虛擬語氣His pale face suggested that he was ill, so his mother suggested he go to hospital.They advised that the goods had arrived and advised we should take them away as soon as possible. 考點三特殊句型中的虛擬語氣1it is (high/about) time (that).句型中的虛擬語氣。句型“it is (high/about) time (that).”后面也可跟虛擬語氣，從句中常用過去式。有時也用“should動詞原形”，意為“該是的時候了”。It is time (that) we went home.It's high time that we _ ourselves to environmental protection and ecological improvement.Ahae devoted BdevotedCare devoting Dhad devoted2if only引導的感嘆句中的虛擬語氣。在“if only”引導的感嘆句中，要求用虛擬語氣，表示愿望。用過去時或“would/could/might動詞原形”表示與現(xiàn)在或?qū)硎聦嵪喾吹脑竿?；用過去完成時表示與過去事實相反的愿望。If only I had not been ill last week!3as if從句中的虛擬語氣。as if從句中，看語境是否與事實相反而選擇是否使用虛擬語氣。It looks as if it's going to rain.The kid talks as if he were a grown­up. 考題印證Don't handle the vase as if it _ made of steel.Ais BwereChas been D. had been專心-專注-專業(yè)