情态动词和虚拟语气.doc

情态动词主要用来表示说话人的情感、态度等，是中学英语语法的重点，也是高考的热点，是单项填空必考的一个知识点。情态动词在近五年高考中主要考查四点：情态动词表示推测和可能性的用法；情态动词与虚拟语气；情态动词表达“情感、态度、语气等”；情态动词表示 “必要性”等方面的用法。虚拟语气的考点主要集中在名词性从句、条件句中的用法，以及错综条件句中虚拟语气的应用。1、 概念1. 什么是情态动词本身有一定词义，是表达说话人的情感、态度、语气的词，其作用是给动词增添感情色彩表现形式：情态动词+动词原形/be2. 特点没有人称和数的变化不能直接跟宾语，必须搭配实义动词或be动词的原形情态动词的过去式往往不表时态，而表示更加委婉的语气。例句：Can/could you help me?2. 情态动词的表现形式1） 情态动词+do 例句：We must help each other to overcome the difficulties. You shouldnt be so careless.2） 情态动词+be doing 例句：She must be sleeping now. My mother may/might be cooking now3） 情态动词+be done 例句：Difficulties can and must be overcome. Something must be done to stop pollution.4） 情态动词+have done 例句：You ought to have come earlier. They might have finished the work.2、 情态动词的分类1. 只能作情态动词：must, can/could, may/might2. 可作情态动词也可作助动词的：will/would, shall/should3. 可作情态动词有可作实义动词的：need， dare4. 具有情态动词特征的：ought to, have to, be able to3、 分类讲解1.can /could 1)表示能力：会，在表示过去的能力时用could 例句：I can swim. Lucy can dance well and her mother could dance well when she was young. The cinema can seat 500 people. I could not read such an easy book when I was 7 years old.2) 表允许，许可常用在口语中，此时could 不表示过去式，而表示语气上比can更客气。例句：-Could I use your dictionary? -Yes,go ahead./Yes, you can.(不可以说Yes, you could.) He asked me whether he could take the book out of the reading room.一、 情态动词表推测的用法 情态动词 意义 语气 句式 语境 例句 备注 must一定 可能性最大 肯定句 对具体事实的判断A：Look，someone is coming. Who can it be? B: It may be our headmaster. A: It cant be him. He has gone to Shanghai. B: It must be Mr. Wang. He looks like our headmaster. That may not be true. He couldnt have discovered the truth. 对现在的行为或状态的推测：must/may/might/can/coulddo 对过去的行为或状态的推测：must/may/might/can/could have done may/might(might可能性小于may)可能可能性较小，尤其might最不肯定肯定句、否定句(可能不)can/could (could可能性小于can)可能疑问句、否定句(不可能)、(could有时也用于肯定句)有时会肯定句情态动词 意义 语气 句式 语境 例句 备注 should /ought to应该 ，理应 理论上Its 8 oclock now. He should be in the office now. Hi, Mum! Im on the bus. I should be home in about ten minutes. 常表示在一段时间内可能发生的事或某人的期望。一般句末有时间状语，或有语境暗示。所表示的猜测发生的可能性很大。 注意：should (ought to)表示推测是高考考查的重点和难点。如：When can I come for the photos？I need them tomorrow afternoon.They _ be ready by 12：00. Acan Bshould Cmight Dneed【解析】 BA项表示推测时常用于否定句和疑问句中。C项表示推测语气不太肯定。should意为“按理说，理应”，既回答了顾客的询问，不失礼貌，又为照片有可能尚未洗好，顾客到时取不到留下了回旋的余地，体现了店主的精明与用词经过仔细推敲。 二、情态动词的其他用法1can, could, may, might情态动词意义 例句 备注 can/could能力 I can see some birds flying in the sky. Could the girl read before she went to school? could表示泛指过去的某一能力。表示过去有能力并且成功地做了某事，通常用was/were able to do，相当于managed to do/succeeded in doing。如：Because he practised hard, he was able to pass the driving test. 情态动词意义 例句 备注 can/could允许(有时可与may互换) Can/May I have a look at your photos？ can与could、may与might不表时态差异，只是语气上的差别，could/might比can/may更委婉。注意在回答时不能用could/ might。 请求 Can/Could you lend me a hand？Yes, I can. 情态动词意义 例句 备注 may/might允许或请求 You may take this if you like.May/Might I ask for a photo of your baby？ can与could、may与might不表时态差异，只是语气上的差别，could/might比can/may更委婉。注意在回答时不能用could/ might。 2.must, should 情态动词意义 例句 备注 must 必须 We must help each other to overcome the difficulties. Must I finish the work today？No, you neednt/you dont have to./Yes, you must. You mustnt take photos here, and it is forbidden. must表示主观意志，have to表示客观。如：They had to speed up, for the weather turned terrible. Must I/we？的否定回答不能用mustnt。 偏要硬要非要Why must you always interrupt me？Can I borrow your car, Mum？If you must. 表示与说话人愿望相反及不耐烦。 情态动词意义 例句 备注 should 应该(常与oughtto通用)You should be polite to the old. ought to 的否定式：ought not to(oughtnt to)；疑问式：Ought to？ 竟然 It is strange that he should react in this way. 表示惊讶、意外等语气。 万一 Should anyone phone, tell them I will call back later. ( If anyone should phone)If I should go there tomorrow, I would go to see her. 用于if从句中强调“万一”，或用于虚拟语气。 3. need, dare 情态动词例句 注意事项 needI neednt go at once. Need you go at once？Yes，I must. /No, I neednt.need可以作实义动词，用于各种句式。如：I need to go at once.I dont need to go at once. Do you need to go at once？Yes，I do.need作情态动词常用于否定、疑问或条件句中。dareHe darent cross the river.How dare you say that to me？dare和need一样，既可以作情态动词，也可用作实义动词。用作情态动词时，主要用于否定句、疑问句和条件句。用作实义动词时，可用于各种句式。如：He didnt dare (to) go out alone at night. (在否定句中to有时可省略) 4.shall/will/would情态动词意义 例句 备注 shall 表示征询意见。 Shall I help you？ 用于第一、第三人称疑问句中。 表示说话人的意愿，有“命令，允诺，警告，决心”等意思。 You shall do as I say. (命令)You shall have the book tomorrow. (允诺)If you dont get out, I shall knock you down. (警告)用于第二、第三人称。 4.shall/will/would情态动词意义 例句 备注 will/would表示意愿 I will do everything for you. None is so blind as those who wont see. 表请求 Will/ Would you please close the window？ 用于疑问句中。would更委婉 表示某种倾向或习惯性动作 Fish will die without water. Every time she was in trouble，she would turn to him for help. (would指过去某一段时间的情况，常与表示过去的时间状语连用，意为“总是，总会”，后面只能接动作性的动词。) used to表示与现在的情况相反，表示“过去如此而现在不再这样”。其后既可接表动作的动词，也可接表状态的动词。如：There used to be an apple tree in front of the house.4.shall/will/would情态动词意义 例句 备注 will/would表示功能(能，行) If you dont have a pen, a pencil will do.We tried the door again，but it wouldnt open. 与否定词连用常表示“拒绝”。 表示推测(可能、大概) This will be the house you are looking for. I would be about ten when my father left home.二、 情态动词have done 情态动词意义 例句 备注 must have done；may/might have done；can/could have done一定(肯定句)；可能(肯定句和否定句)；可能(疑问句和否定句)You cant/couldnt have met my grandmother. She died before you were born. 对过去的事情的推测 might have done; couldhave done；would have done本来可能做而未做；本可以做而未做；本来会做而未做He might have given you more help, even though he was very busy.We could have walked there, and it was so near.与过去事实相反的虚拟表达 情态动词意义 例句 备注 should/ought to have done本应该做而未做 Your brother has failed English exam again. You ought to have given him more help. 表示责备neednt have done本不需要做但却做了You neednt have wakened me up; I dont have to go to work today.四、虚拟语气虚拟语气表示说话人所说的话不是事实，而是一种假设、愿望、怀疑或推测。1 虚拟语气在条件句中的用法 if从句主句与现在事实相反if主语动词过去式主语should/would/could/might动词原形与过去事实相反If 主语had过去分词主语should/would/could/might have 过去分词与将来事实相反(1) if主语动词过去式主语should/would/could/ might动词原形(2)if主语were to动词原形(3) if主语should动词原形If it were to rain tomorrow, I should not drive my car. 如果明天下雨的话，我就不开车了。(明天的情况还不知道)If I had done it in time, I should have had a good time. 如果我及时做的话，日子就好过多了。(可惜当时没能及时做)注意：(1)主句中的should通常用于第一人称，would可用于任何人称。(2)条件句中如果动词是be，其过去式所有人称的单复数都可用were；在第一、三人称单数的口语中，可用was代替were。但在if I were you中，不能说成if I was you。(3)当条件从句的行为与主句所表示的行为所发生的时间不一致时，主从句中动词的形式要根据它所标示的时间作出相应的调整，这就是所谓的“错综条件虚拟语气”。如：If they had studied hard, they could do it easily now.如果他们以前努力学习的话，现在干得就会容易些了。If he had not taken my advice, he wouldnt do it much better like this.如果他不听我的建议，他就不会干得这么好了。(4)在条件句中，如果有were, had, should等，则可省略if，但应注意把were, had, should等提到从句主语之前。如：If he were to come, I would join him in the discussion. Were he to come, I would join him in the discussion. 如果他来，我将和他一道参加讨论。(5)有些虚拟条件句没有从句，虚拟条件句是通过上下文或介词短语表示出来的。如：But for air and water, there would be no life on the earth. 要是没有空气和水，地球上就没有生命。(介词短语but for提供了虚拟条件)With your help, we might finish the plan earlier. 要是有你的帮助，我们就可以早些完成任务。(介词短语with your help充当虚拟条件句)2虚拟语气在wish从句中的用法专题八 正面解读宾语从句愿望I wish主语动词过去式现在不能实现的愿望主语had过去分词过去不能实现的愿望主语would/might动词原形将来不能实现的愿望I wish I were a doctor. 我希望我是个医生就好了。(现在)I wish that the rain would stop. 我希望雨能停下来。(将来)I wish that he had not made so much fuss about it. 我希望他不要把事情搞大了。(过去)3虚拟语气在名词性从句中的使用(1)在insist；command，order；demand，request，require，desire；advise, propose, suggest，recommend等表示“命令、要求、建议”的动词后接的宾语从句中要使用虚拟语气。如：He suggests that she (should) leave the house at once.他要她立刻离开这所房子。He proposed that we (should) deal with the problem by the view of development. 他建议我们应该用发展的眼光处理这个问题。(2)与上述动词相对应的名词suggestion, order, demand , proposal 等后的表语从句、同位语从句中也要使用虚拟语气(should可省略)。如：My proposal is that we (should) set a deadline for handing in the plan.我的建议是为这个计划设定一个上交的期限。(3)在It be suggested (ordered, demanded, proposed, )that 结构中，主语从句中也要使用虚拟语气。如：Its required that every student be on time for school. 要求每个学生准时到校。(4)在do you suggest/recommend用在特殊疑问句中作插入语时，句子的动词也使用虚拟语气，即“should动词原形”的形式，其中should可以省略。如：What type of computer do you recommend/ suggest we (should) buy?你建议我们买什么类型的电脑呢？(5)在Itsnecessary，essential，important, strange, natural等形容词 that从句或Its a pity，a shame等名词 that 从句中，谓语动词可以使用should do。如：It is necessary that the badly wounded man should be treated immediately. 这位重伤员必须马上治疗。Its a pity that you should be so careless.你竟然如此粗心，真是可惜。4虚拟语气在状语从句中的用法在as if/though引导的状语从句中，谓语动词用过去式表示与现在相反的情况；用过去完成式，表示与过去相反的情况等。其变化与wish后的宾语从句的变化相同。如：Ive loved you as if you were my relative.我一直爱你仿佛你是我的亲人。5虚拟语气在其他一些句型中的用法(1)Its high time that从句中，谓语动词可以使用过去式，也可使用should动词原形；表示“早该了”，其中should不可省略。如：Its high time we got up/should get up. 我们早该起床了。(2)would rather从句中，谓语动词用过去式表示与现在或将来的情况相反；用过去完成式，表示与过去的情况相反。如：I would rather you came tomorrow. 我宁愿你明天来。(3)if only要是多好啊。如：If only you hadnt offended him. 你当时不惹他就好了。If only he could come tomorrow. 他明天能来就好了。(4)其他一些表示祝愿的句型。如：May you succeed！祝你成功！Long live the Peoples Republic of China. 中华人民共和国万岁！1. 【误】 The streets are all dry; it mustnt have rained last night. 【正】 The streets are all dry; it cant have rained last night. 【解析】 对某一事实的否定推测不能用must，而要用cant 或couldnt表示“不可能”。2【误】 I didnt see Mary at the meeting yesterday. She might be ill, I guess. 【正】 I didnt see Mary at the meeting yesterday. She might have been ill, I guess. 【解析】 猜的事情发生在昨天，因此要用情态动词have done形式，当动词是be时，很容易忽略它的时态意义，要特别留意。3【误】 He must be very friendly at times. 【正】 He can be very friendly at times. 【解析】 句意为：他有时会很友好。可知此处并非对现在的状态进行推测，而是一种理论上的可能性，因此用can。4【误】 I cant find my keys. I may/might forget them on the playground yesterday. 【正】 I cant find my keys. I may/might have left them on the playground yesterday. 【解析】 表示对过去情况的推测，通常用must/may/might have done sth. 另外，表示“把忘记在某地”应用动词leave。5【误】 The fire spread through the hotel quickly, but everyone could get out. 【正】 The fire spread through the hotel quickly, but everyone was able to get out. 【解析】 表示在过去成功地做到了某事，肯定句中通常用was/were able to do sth.。6【误】 Will I open the window for you?【正】 Shall I open the window for you?【解析】 shall与第一、第三人称连用，表示征求意见或请求指示，这时不可用will。will通常与第二人称连用，即Will you？7【误】 The plant is dead. Maybe I should give more water. 【正】 The plant is dead. Maybe I should have given more water. 【解析】 根据第一句可知，植物已经死亡，所以应该是自责：本应该多浇些水的。要用should have done形式表示“本应该做而未做”。8【误】 Hadnt they saved us, we would have been drowned in the stormy river. 【正】 Had they not saved us, we would have been drowned in the stormy river. 【正】 If they had not saved us, we would have been drowned in the stormy river. 【解析】 当条件中含有were, had, should等时，可省略if，从而把were, had, should提到主语之前。若条件句为否定句，则只把were, had, should提前，not仍放在主语之后。9【误】 If only I saw the film yesterday. 【正】 If only I had seen the film yesterday. 【解析】 if only后句子若表示过去的一种愿望，其谓语动词应用过去完成式，即if only sb. had done sth. 。1Everyone in my class passed the exam. Oh，really？It _ difficult. Acant have been Bneednt have beenCmust be Dmightnt be【解析】 A考查情态动词。对过去进行推测，表示“一定不”应使用 cant have done。句意为：“我们班上每个人都通过了考试。”“哦，真的吗？那题目一定不难。”22009安徽卷 Some people who dont like to talk much are not necessarily shy；they _ just be quiet people.Amust Bmay Cshould Dwould【解析】 B句意为：有些人不喜欢讲话不一定是害羞，他们可能是安静的人。此处用may表示“可能”之意。3Why didnt you answer the phone last night?I _ when you called. Ahad to have sleptBhad to be sleepingCmust have been sleepingDmust have slept【解析】 C由时间状语和结合语境来看，这是对过去某个时间点正在发生事情的肯定推测，再结合题意，应该是must have been doing结构，选C。4When I lived with my roommates in the university, we _ often talk into the night. Amight Bmust Cshould Dwould【解析】 D这里描述的是过去经常发生的动作(或过去经常做的事情)。5This is the first time I _ my first picture with my own hands. It is time that you _ a picture for me. Atook; took Bhave taken; tookCtook; will take Dwill take; have taken【解析】 BThis/It is the first time that中，从句的谓语动词通常用现在完成式；Its (high) time that中，从句谓语动词通常用一般过去式(即虚拟语气)，意为“该是做的时候了”。6Why hasnt Jack come back yet？_anything have happened to him?Im not sure, but I guess something_. AMay；must have BCan；may haveCMust；may DDare；might have【解析】 B考查情态动词。在一般疑问句或特殊疑问句中表推测时常用can或could，推测发生过的事情时情态动词后要接完成式，只能选B。7It is usually warm in my hometown in March, but it_ be rather cold sometimes. Amust Bcan Cshould Dwould【解析】 Bcan用在肯定句中可以指“有时会，可能会”，表示客观情况或逻辑上的可能性。句意为：三月份在我们家乡通常比较暖和，但有时也会非常冷。8Liza_ well not want to go on the tripshe hates traveling. Awill Bcan Cmust Dmay【解析】 Dmay well (not) do sth.意为“很可能(不)干某事，完全(没)有可能干某事”。9Look at the floor, Tom！_you watch TV while having a meal?AShould BCouldCWould DMust【解析】 Dmust 表示与说话人愿望相反或不耐烦“非得、偏要”。如：Must you make so much noise？你就非得弄出这么大声吗？10The soccer team has been doing well this season，so they _win the championship. Ashould Bmight Cwould Dmust【解析】 A本题考查情态动词。句意为：这个足球队在这个季度训练得很好，因此，他们应该会赢得冠军。根据常理进行推测表示“应该”时用should。11When the ship sailed out from Thailand, the 16 sailors on board _ that only half of them would return again. Awill never think Bcan never thinkCneednt have thought Dcouldnt have thought【解析】 D考查“情态动词完成式”的用法。根据句意“当这艘轮船从泰国驶出的时候，船上的16名船员不会想到他们当中只有一半的人会返回”可知，这里表示对过去事情的否定推测，选D。12What does the sign over there read?No person _ smoke or carry a lighted cigarette in this area. Awill Bshall Cmay Dmust【解析】 B考查情态动词的特殊用法。答句句意为：任何人在这里都不能吸烟或者是携带点燃的香烟。shall在这里表示强制，用于法令、条约、规章中，意为“必须，应该”。专题八 实战演练13Its hard to believe that such a greedy man_ donate so much to Project Hope. Amay Bneed Ccan Dshall【解析】 C考查情态动词的特殊用法。句意为：这么贪婪的人竟能为希望工程捐出这么多钱，真是难以置信！can在这里表示惊讶、不相信，意为“居然会，竟能”。14For environmental reasons，we _ as well take these waste products and have them recycled. Ashould Bwould Cmight Dcould【解析】 C考查情态动词。所填词与as well构成固定搭配，意思是不妨，用might，选C。15We _ here at lunch time; we were delayed at the airport, though. Acould be Bshould beCmust have been Dwould have been【解析】 Dwould have done sth.表示与已经发生的事实相反，意思是“本来会但实际没有”。句意为：我们本来能在午餐时到达，但我们在机场被延误了。16Jenny took the 8：00 bus to Guangzhou this morning. Really？He _ the 9：00 train. Its much more comfortable and safer to travel by train. Acould have taken Bshould takeCmust have taken Dcan take【解析】 A考查情态动词的用法。上句表示珍妮已乘坐8点的汽车去了广州。答句句意为：她本可以坐9点的火车去的，坐火车舒服得多，安全得多。“情态动词could完成式”表示“本来可以，而实际上并没有那么做”。172010四川卷 _ I take the book out?Im afraid not. AWill BMay CMust DNeed【解析】 B考查情态动词词义辨析。may用于一般疑问句，表示请求。182010安徽卷 Jack described his father，who _ a brave boy many years ago，as a strongwilled man. Awould be Bwould have beenCmust be Dmust have been【解析】 D考查情态动词。句意为：杰克把他父亲描写成一个有坚强意志的人，他很多年前就一定是一个勇敢的男孩。根据many years ago可知，是对过去事情的推测。would have been多用于条件句的虚拟语气中。192010浙江卷 Had I known about this computer program，a huge amount of time and energy_. Awould have been saved Bhad been savedCwill be saved Dwas saved【解析】 A本题考查虚拟语气。根据Had I known提示，可知此句是虚拟语气，且与过去事实相反，故主句谓语用would have done的形式。此外本句还是被动，选A。202010湖南卷 You _ buy a gift，but you can if you want to. Amust BmustntChave to Ddont have to【解析】 D考查情态动词。dont have to意为“没有必要”，符合语境。句意为：你没有必要买礼物，但如果你想买的话，你也可以买。212010陕西卷 May I take this book out of the reading room?No，you_. You read it in here. Amightnt Bwont Cneednt Dmustnt【解析】 D本题考查情态动词的用法。表示“禁止；千万别做某事”时，要用mustnt。222010江西卷 I have told you the truth. _ I keep repeating it?AMust BCan CMay DWill【解析】 A考查情态动词的用法。句意为：我已经告诉你真相了。要我一再重复吗？must在此用于加强语气，意为“必须吗？非得吗？”232010江苏卷 I havent got the reference book yet，but Ill have a test on the subject next month. Dont worry. You _have it by Friday. Acould BshallCmust Dmay【解析】 B本题考查情态动词。当主语为第二、三人称时，情态动词shall表示说话人给对方命令、警告、允诺或威胁，本句表示允诺。242010江苏卷 George is going to talk about the geography of his country，but Id rather he _ more on its culture. Afocus BfocusedCwould focus Dhad focused【解析】 B本题考查虚拟语气。would rather从句表示对现在或将来虚拟时应使用一般过去时。252010全国卷 Just be patient. You _ expect the world to change so soon. Acant BneedntCmay not Dwill not【解析】 A考查情态动词的用法。cant表示“不能”，语气强烈。262010福建卷 Teachers recommend parents _ their children under 12 to ride bicycles to school for safety. Anot allow Bdo not allowCmustnt allow Dcouldnt allow【解析】 A考查虚拟语气。句意为：教师们建议：为了孩子们的安全，父母不应让12岁以下的孩子骑自行车去学校。recommend意为“建议”，其后接的宾语从句采用虚拟语气，从句谓语动词用“should动词原形”的形式，should可以省略。272010天津卷 Mark _ have hurried. After driving at top speed，he arrived half an hour early. Aneednt BwouldntCmustnt Dcouldnt【解析】 Aneednt have done 本没有必要做某事，实际上做了。282010重庆卷 You _ park here! Its an emergency exit. Awouldnt Bnee