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1、一、情态动词1情态动词表能力I am starving to death.I can eat two bowls of rice now.我快饿死了，现在我能吃两碗米饭。(现在的能力)If you have a good sleep，you will be able to work out this problem.如果你好好睡一觉，你将能够解出这道题。(将来的能力)The fire spread through the hotel very quickly but everyone was able to get out.尽管这场大火迅速蔓延到了整个宾馆，但是每个人都能够逃出去。(过去有能力
2、做并且成功地做了某事)2情态动词表推测(1)情态动词动词原形表现在推测情态动词情态动词肯定式肯定式否定式否定式疑问式疑问式must必定，一定必定，一定will很可能，大概，愿意，很可能，大概，愿意，总是总是不会，不愿不会，不愿会会吗？吗？would比比will可能性小；还可能性小；还可表可表“过去常常过去常常”比比wont语气弱语气弱比比will语气弱语气弱should应该应该(合乎道理的情合乎道理的情况或结果况或结果)情态动词情态动词肯定式肯定式否定式否定式疑问式疑问式ought to理应，应该理应，应该(同同should)can很少用，若用时则表很少用，若用时则表理论上的可能性理论上的可能
3、性不可能不可能有可能吗？有可能吗？could(可疑的可疑的)可能可能不可能不可能有可能吗？有可能吗？(语语气比气比can弱弱)may或许，也许，也说不或许，也许，也说不定定可能不可能不might比比may语气还弱语气还弱比比may not还弱还弱(图中表示此用法时不表推测，表其他含义)Accidents can happen on such rainy days.多雨的天气可能会发生事故。This may/might be done by him.这事可能是他干的。(might语气更弱)Its nearly seven oclock.He should be here at any momen
4、t.快七点了，他理应随时在这儿的。(2)“情态动词have done”结构用于对过去事情的推测。I didnt hear the phone.I must have been asleep.我当时没有听到电话响，我一定是睡着了。Tom hasnt come back yet.He may have missed the bus again.汤姆还没有回来，他可能又没赶上班车。Jack cant have arrived yet；otherwise he would have telephoned me.杰克不可能来到，否则，他会给我来电话的。3情态动词表责备语气(1)should (ought
5、 to) have done 本应该表示过去应该做而(实际)没有做的事情，含有责备或遗憾的语气，其否定形式为“should not/ought not to have done”。I told Sally how to get there，but perhaps I should have written it out for her.当时我告诉了沙丽如何去那儿，但或许我还是该给她写出来为好。I was really anxious about you.You shouldnt/ought not to have left home without a word.我当时真的很为你担心。你不该一
6、句话不说就离家出走的。【注意】should have done还可以表示惊讶、赞叹等情绪。I cant think why he should have said that；it wasnt my fault.我想不出他为什么竟然说出那样的话，要知道可不是我的错呀。(2)could/might have done本来能够(会)表示过去本来可以(能够)做某事，但实际上没有做到。I stayed at a hotel while in New York.在纽约时我住在了一家宾馆里。Oh，did you？You could have stayed with Barbara.是吗？你本来是可以和芭芭拉
7、住在一起的。(3)neednt have done本来不需要表示过去本来没有必要做某事，但事实上却做了。There was plenty of time.She neednt have hurried.当时时间很充足，她本没有必要那么匆忙的。4表示请求、允许(1)当对方是决策者时，你代表你自己(I，we)，或代表第三者(he，she，they)向对方(you)征求意见或向对方请示(即主语是第一人称、第三人称)，用shall，此外此种用法还可用May(Might)/Can(Could) I.？Can (Could) he/we.？等句型；当主语是第二人称时，用Would/Will/Could/C
8、an you.?Shall we begin our class？我们开始上课好吗？Shall the driver wait outside？让司机在外面等着吗？Can/Could I leave now？我现在可以走了吗？Would you do me a favor？请帮我个忙好吗？(2)当你自己(I)是决策者，给对方(you)或第三者(he，she，they)以命令、警告、允诺或威胁时，要用shall，此外当宣布法律、规定时，也要用此用法。Candidates shall remain in their seats until all the papers have been coll
9、ected.试卷全部收回后应试人才可离开座位。(3)could/might，would和should的委婉功能Could/Might I use your bike tomorrow morning?明天上午我可以用你的自行车吗？Yes，you can/may.行，可以。(否定：No，Im afraid not.)不可说：Yes，you could/might.回答允许时，用could/might 表委婉是不恰当的。You are mistaken，I should say.要我说，你是搞错了。I should advise you not to do that.我倒是劝你别这样做。Would
10、 you please take a message for him?你愿意给他捎个口信吗？5情态动词的特殊用法(1)cannot(或never等否定词)与enough连用表示“再也不为过”。cannot butdo sth.表示“不得不，只好”。I can not but choose to go.我只好去。(2)may可以用于祈使句，表示祝愿。May we never forget each other.愿我们彼此永不相忘。May you return in safety.愿你平安归来。(3)may well和may as well结构。“may well动词原形”是一种常用结构，意为“完
11、全能，很可能”，相当于to be very likely to。He may well be proud of his son.他大可为他的儿子感到自豪。Her appearance has changed so much that you may well not recognize her.她的模样变化太大，你很可能认不出她了。“may as well动词原形”意为“最好，满可以，倒不如”。You may as well do it at once.你最好马上就做这件事。We may as well stay where we are.我们留在现在的地方倒也不错。(4)Why/Howsho
12、uld结构表示说话人对某事不能理解、感到意外、惊异等意思，意为“竟会”。Why should you be so late today?你今天怎么来得这么晚？How should I know?我怎么会知道？(意为：我不知道。)(5)must表示“偏要、硬要”做某事。Must you make so much noise?你非得弄出这么大声吗？If you must smoke，please go out.如果你偏要吸烟，那你就出去吧。(6)need和dare的用法need和dare两者既可用作情态动词也可用作行为动词。作行为动词时，有人称和数的变化，可用于肯定句、否定句或疑问句中，构成否定句
13、或疑问句时要用助动词do，does，did；作情态动词时，没有人称和数的变化(dare的过去式dared)，直接接动词原形，只用于否定句和疑问句中，构成否定句和疑问句时不用助动词。另外，dare作情态动词时，还可用于条件句中，过去式为dared；作行为动词时，dare用于疑问句或否定句，后面的to也可省略；I dare say是习惯说法，意为“我想，大概”。He neednt do it.(情态动词)He doesnt need to do it.(行为动词)他不需要做这件事。I didnt know whether he dared say that to him.(情态动词，有时态变化)我
14、不知道他是否敢对他说那件事。He didnt dare (to) do that.(行为动词)He dared not do it.(情态动词)他不敢那样做。【注意】need作行为动词时，还可表示“需要”，后接v.ing形式的主动形式表示被动含义。The floor needs sweeping.这地需要打扫了。二、虚拟语气虚拟语气用来表示说话人的主观愿望、建议、命令、要求或假设等，表示一种不可能实现的或与事实相反的愿望。1虚拟语气在条件句中的应用虚拟条件句虚拟条件句主句主句例句例句与现与现在事在事实相实相反的反的假设假设If主语动词的主语动词的过去式过去式(be动词用动词用were)主语主语
15、should/would/could/might动动词原形词原形If I had time，I would go to the concert. If I were you，I should seize the chance.与过与过去事去事实相实相反的反的假设假设If主语主语had过过去分词去分词主语主语should/would/could/mighthave过过去分词去分词If I had practised more，I would have passed the driving exam.与将与将来事来事实相实相反的反的假设假设If主语动词主语动词过去式过去式If主语主语were to
16、动词原形动词原形If主语主语should动词原形动词原形主语主语should/would/could/might动动词原形词原形If you came tomorrow，we would have the meeting. If it were to rain tomorrow，the sports meeting would be put off. If he should not come tomorrow，we should put off the meeting till next Monday.【注意】(1)混合条件句主句与从句的动作发生在不同的时间，这时主、从句谓语动词的虚拟语气形
17、式因时间不同而不同，这叫做混合条件句。If it had rained last night，it would be very cold today.如果昨天晚上下了雨，今天就会非常冷了。(2)虚拟条件句的倒装虚拟条件句的从句部分如果含有were，should或had，可将if省略，再把were，should或had移到从句句首，实行倒装。Should it rain，the crops would be saved.Were it to rain，the crops would be saved.要是下了雨，庄稼就会有救了。2含蓄条件句有时假设的情况并不以条件从句表示出来，而是通过一个介词短
18、语来表示出来。如supposing(假如)，without(没有)，but for(要不是)。Without electricity，there would not be modern industry.要是没有电的话，就不会有现代工业了。But for the leadership of the Party，we could not live such a happy life.要不是党的领导，我们就不会生活得这么幸福。3虚拟语气用于宾语从句中(1)当主句的谓语动词为“suggest，advise，insist，order，demand，ask，desire，require，recommen
19、d，request，urge”等表示“建议”、“命令”、“请求”和“要求”的动词时，其后的宾语从句中要用“should动词原形”(should可省略)。I suggest that we (should) hold a meeting tonight.我建议我们今晚开个会。We advise that steps (should) be taken at once.我们建议要立刻采取措施。They insisted that he (should) begin the work at once.他们坚持让他立刻开始工作。但suggest，insist不表示建议或坚持要某人做某事时，即它们用于其
20、本意暗示、表明或坚持认为时，宾语从句用陈述语气。She insists that she is right.她坚持认为她是对的。His face suggested that he was angry.他的脸色表明他生气了。(2)当主句动词为wish，表示“但愿”，“要是该多好”之意时，其后的宾语从句使用虚拟语气形式。动词用过去式来说明与现在的事实相反(be动词一律用were)。I wish I were as strong as you.我要是像你一样强壮就好了。I wish I remembered his address.我要是记住他的地址就好了。动词用过去完成式或would/could
21、have过去分词说明与过去的事实相反。We wish we had paid more attention to our pronunciation.我们以前要是能更注意我们的发音就好了。He wished he had stayed at home.他但愿他呆在了家里。情态动词“would，could，might”等后接动词原形，表示将来不大可能实现的愿望(通常不用should)。I wish he would try again.我希望他再试一下。We wish he could come.我们希望他能来。(3)在would rather，would sooner，had rather，w
22、ould (just) as soon，would prefer之后的宾语从句中，其动词用虚拟语气，表示句子的主语(某人)宁愿让另一人做某事或对过去做的事的懊悔。用动词过去式表示现在或将来要做的事。I would rather you went home now.我宁愿让你现在就回家。Do not come tomorrow.I would rather you came next weekend.明天别来，我宁愿你下个周末来。用动词的过去完成式表示过去的动作。I would rather you had not done that.我真希望(宁愿)你没做过那件事。4虚拟语气用于主语从句中(1
23、)在句型“It is/was过去分词that从句”中，当过去分词为：insisted，required，demanded，decided，proposed，urged，requested，suggested，recommended，ordered等时，从句中要用“should动词原形”(should可省略)。It is requested that Miss Zhang (should) give a performance at the party.在晚会上张小姐被请求表演一个节目。(2)在句型“It is/was 形容词that从句”中，当形容词为：natural，necessary，im
24、portant，strange等时，从句中要用“should动词原形”(should可省略)。It is important and necessary that we should master a foreign language.掌握一门外语对我们来说是重要的和必要的。It is strange that he (should) refuse your help.他竟然拒绝你们的帮助，真奇怪。5虚拟语气用于同位语从句或表语从句中在名词demand，desire，requirement，advice，recommendation，suggestion，order，proposal，plan
25、，idea等后面的同位语从句或表语从句中，用“should动词原形”(should可省略)。但在as if，as though引导的表语从句中，从句中谓语用动词过去式或过去完成式，表示对现在或过去的虚拟。I made a suggestion that we (should) hold a meeting next week.我提出了我们下个星期开会的建议。(同位语从句)His suggestion that the meeting (should) be held in this room has been accepted.他的关于在这个房间召开会议的建议被采纳了。(同位语从句)My id
26、ea is that we (should) get more people to attend the conference.我的想法是我们多找些人来参加会议。(表语从句)He looks as if he were tired.他面带倦容。(表语从句)6虚拟语气用于定语从句中在句型“It is (high) time(that)从句”中，谓语需用虚拟语气。用过去式表示现在或将来的意念，意为“现在是该做某事的时候了”。It is (high) time (that) we went home.我们该回家了。7虚拟语气用于方式状语从句中由as if和as though等引导的方式状语从句中，如果从句所表达的情况是虚拟的，则：(1)常用动词的过去式来表示与现在或当时的情况相反；The young man with long hair walks as if he were a girl.留长发的那个小伙子走起路来就像个小姑娘。(2)常用过去完成式来表示与过去的情况相反。The injured man acted as if nothing had happened.那个受伤的男子行动起来仿佛什么也没发生一样。
