情态动词和虚拟语气讲义.docVIP

情态动词和虚拟语气讲义考点一：情态动词的基本用法1. can, could, may, might的用法1) can表示能力，意为“能够；懂得；会”。could表示过去的能力；其将来时用be able to代替。This machine can perform two million calculations per second. I can speak five languages.注意：be able to表示“能够做某事而且做成功了”。He was able to do that without any help. 他不需要任何帮助就完成了这项工作。2) can, could, may, might表示请求 (permission)、允许或许可。常用在口语中，其中的could语气较委婉，不用于肯定句，答语要用can；could都还表示委婉客气的提出问题或陈述看法；might表示委婉的请求。The goalkeeper cant handle the ball outside the penalty area (禁区).Could I use your bike? 我可以用你的自行车吗？Yes, you can./Im afraid not. 可以，用吧。No, you cant/mustnt. 不行。May/Can take the book out? 我可以把这本书带走吗？Yes, you may/can. 可以。No, you may not. 不可以。（委婉）No, you cant/mustnt. 不行。（强烈）3) can与表示感官和思维的动词连用。You can really taste the garlic in that soup.You can imagine how annoyed she was!2. must的用法。must既表示义务或强制，意为“必须；一定要”；还可表示肯定性，意为“必然会；肯定会”；作“偏要；硬要”解时，用于第二人称时，表示不耐烦或令人不愉快的事情；用于其他人称，表示主语“固执”的意味。If you cant finish the book by then, you must come and renew it. Im afraid I must go now; I promised to be home at ten. Dont bet on the horse race; you must lose in the long run.If you must know, Im going to help him look for an apartment. Jane was never a pleasant young girl. After you gave her your advice, she must go and do the opposite.must的否定形式有两种：当must表示“强制或义务”时，其否定意义为“一定不要”，表示不许或禁止，将must do改为must not do；当must表示“必须”时，其否定含义为“不必”，将must do改为need not do或dont have to。We mustnt waste our time. 我们不应该浪费时间。You need not/dont have to get up at six tomorrow morning. 明天早上你不必六点起床。注意：1) must可以用作名词，意为“必须有的东西（做的事）。Dont miss latest play; its a must. /Warm clothes are a must in the mountains.2) 词组be sure to, be certain to, be bound to, be due to都有“一定；肯定；务必”等意义。He informed us that the boat was due to leave at 4. /The plan is bound to succeed.3. shall的用法。在疑问句中，用于第一、三人称，表示征求对方的意见；用于第二、三人称时表允诺，警告，命令，威胁等；在法律、条约、规章等文件中，表示义务、规定。What shall I wear on the journey? /Shall he start at once or wait for a while?She shall get her share. /You shall fail if you dont work harder.House owners shall keep their gardens in a neat and ordinary state.Each citizen shall carry his identification card when traveling. 4. should和ought to的用法。should表示“劝告、建议、命令”，其同义词是ought to (否定式ought not to do)；should还可表示义务，意为“应该”；也可表示惊讶，忧虑，惋惜等情绪，意为“竟会；竟然”，常用在Im surprised; It worries me; Its a pity; You cant imagine等结构中。You should/ought to go to class right away. He should do some work, but he doesnt want to.I find it quite astonishing that he should be so rude to you./You cant imagine that a well-behaved gentleman should be rude to a lady.5. will和would的用法。will可以表示意志，决心或愿望；也可表示经常性、习惯性、倾向性，表示某事总是发生或一般如此；也可表请求；还可表示“老是”，用于描述某人奇异或令人烦的习性，用在第三人称。would也可表示愿望，还表示过去的习惯行为，用于第二人称作主语的疑问句中，表示对对方的请求。Surely we will support all the people in the world in their struggle for peace. I will come up and help you clean the room in a moment.Oil will float on water./ Accidents will happen.He will sit there hour after hour looking at the traffic go by./Trish will keep asking silly questions.During the vacation he would visit me every week. 注意：wont或wouldnt表示“坚决地拒绝”.I wont listen to your nonsense./We urged him to take a rest, but he wouldnt hear of it.考点二、情态动词表“可能性”的用法：1. can表可能性，含有惊讶、怀疑、不相信的语气，常用在否定句、疑问句、感叹句中，意为“可能”；can be用于推测某人或某物一时的情况，意为“有时候会”；could表轻微的怀疑或委婉的看法。Can what he said be true? /What can he possibly mean?It can be very cold here at night. /The boy can be very annoying.His story could be true, but I hardly think it is.注意：can表示“可能性”，有时也可用在肯定句中，但表示的是理论上的可能性，不涉及是否真的会发生。The invention can be improved./The word “bank” can have several meanings.2. may表可能性，用于推测，暗指不确定，不用于疑问句，在疑问句中表示“可能”时，通常用be likely to或do you think结构；当句中出现I am afraid, I am not sure等表示不确定含义时，常选用may或might；may表示的可能性比might大一些。It is feared that many workers may lose their jobs this winter. /I am afraid he may be waiting for you.Is she likely to come this afternoon?3. must可以表示推测，只能用在肯定句中，表示“一定”或“必定”之意，其否定形式是cant/couldnt，意为“不可能”。Must be doing表示“现在肯定正在做”。Whose new bike can it be? - It must be Liu Dongs. I know his father has just bought him a new one.You look happy. You must be having a good time.He cant be in Beijing now because I have seen him just now.4. should表示期待，用于表达合理的推断（“应该）或明显的结果（可能），所期待的事是事实。It is three oclock, the football game should begin now.Mary took dancing lessons for years; she should be an excellent dancer.注意：词组be supposed to, be meant to均有“应该；必须”等情态含义。Everybody is supposed to wear a seat belt in the car.考点三、情态动词+不定式的完成式“情态动词+不定式的完成式”在高考中出现的频率也相当高，其中尤以must have done出现次数最多。下表是“情态动词+不定式的完成式”的结构和含义。结构含义could have done过去可以做而实际上没做。“本来可以做”。表推测，过去可能做了某事cant /couldnt have done过去不可能发生的事情，是must have done的否定式。may/might have done对过去发生的行为的推测。“可能会做”。must have done对过去已发生的行为的推断。“一定已做”。need have done本来需要做而实际上已做了。“本有必要做”。neednt have done本来不需要做而实际上没做。“本不必做”。should have done本来应该做而实际上没做。“本应该做”。shouldnt have done本来不应该组哦而实际上做了。“本不应该做”。ought to have done过去应该做而实际上没做。“本应该做”。will have done推测将来某个时间前已经完成。“可能已经做”。You could have done better, but you didnt try your best. 你本可做的更好，但你不尽力。They cant have gone out because the light is on. 他们不可能用光了，因为灯还亮。He may have finished the exercises, but he didnt hand in. 他可能完成了作业，但没交。He is not in. He must have gone to Shanghai. 他不在家，肯定去上海了。You neednt have watered the flowers, for it going to rain. 你本没有必要浇花，因为天要下雨了。You should have started earlier, but you didnt. 你本应该早一点出发的，但你没有。考点四、情态动词的某些惯用语和句型1. can的惯用语1) cannot (help/choose) but+原形 不得不；只能 I cannot help but tell the truth.2) can but+原形 只好；不得不 We can but agree with you3) cannot help doing 不得不；忍不住4) cant help sb. doing sth. 不能使某人不作某事 I cant help saying that.5) cant help it 控制不住，没有办法 Why are you crying? I cant help it.6) cannot tooto 无论怎样也不为过2. may/might的惯用语1) may/might well do 很可能；极有可能These are excellent photographs and we may well be able to use them in our magazine.You might well find that you need more by the weekend.2) may/might as well 最好（had better）Its no good waiting for the bus. We might as well walk.If you are not going to eat that pizza I may as well throw it out.3) may/might as well doas do与其做某事，不如做某事You might as well throw the money away as lend it to him.One may as well not know a thing at all as know it but imperfectly.4) maybut 尽管但是He may be lazy, but he can work very hard when he feel like it.5) may you/he/they etc do sth. 祝愿 May both the bride and groom have long and happy life.3. 用作情态动词的其他短语 1) would rather, would sooner, would (just) as soon, had rather, had better, had sooner可用作情态动词。 The soldier would sooner die than surrender. 这个战士宁可死也不投降。If you dont like to swim, you may just as well stay at home. 如果你不喜欢游泳，最好呆在家里。这些短语后一般直接跟动词原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引导的从句，that 常省去，从句要用虚拟语气。对现在和将来的假设用过去时，对过去的假设用过去完成时。 I would rather you came on Sunday. 我想让你周日来。I would sooner you hadnt asked me to speak yesterday. 我宁愿你昨天没让我发言。2) so that/in order that接may, might, can, should；for fear that后接might, should；in case that后接should。He rested in order that he might work harder.We all seemed afraid to say what was in our minds, for fear that it might start trouble.Better chain up the dog in case he bite/bites.高考链接：1.（2009四川卷）I dont care what people think.Well, you _.A. could B. would C. should D. might2.（2009全国卷I）What do you mean, there are only ten tickets? There _ be twelve.A. should B. would C. will D. shall3.（2009湖南卷） Its the office! So you _ know eating is not allowed here. Oh, sorry. A. must B. will C. may D. need 4.（2009辽宁卷）The traffic is heavy these days. I _ arrive a bit late, so could you save me a place?A. can B. must C. need D. might5.（2009全国卷II ）I cant leave. She told me that I _ stay here until she comes back.A. can B. must C. will D. may6.（2009重庆卷）Hi, Tom . Any idea where Jane is?She _in the classroom . I saw her there just now.A. shall be B. should have beenC. must be D. might have been7.（2009北京卷）One of the few things you _ say about English people with certainty is that they talk a lot about the weather. A. need B. must C. should D. can虚拟语气讲义一、虚拟条件句，即不大可能发生的或与事实相反的情况。1) 很可能与现在或将来的事实相反的条件句。其基本结构是：If + S. +V.（过去式/were）, S. + would/should/could/might + 动词原形。如表示和将来事实相反，if条件句还可用“were to+动词原形”和“should+动词原形”来表示。If从句里的be动词一律用were，没有人称与数的变化。指现在或将来的任何时候，这一结构中所设的条件可能与事实相反，结果从句也不是事实。If I had enough money, I would buy that coat. 如果我有足够的钱，我就买那件外套。Sunny would be in time if she got the four-thirty bus. 如果桑妮搭上4点30分的公共汽车，她就会及时赶到。If I were you, I would accept their invitation. 如果我是你，我就接受他们的邀请。If you were to die tonight, what would you do right now? 如果你今天晚上就要死了，那你现在做什么？2) 和过去事实相反的条件句。其基本结构是：If + S. +V.（过去完成式had done）, S. + would/should/could/might have + 过去分词。此种结构里的条件句所设的条件并未发生，因而结果从句所述的结果也未实现。If the weather had been nice yesterday, we would have gone to the zoo. 如果昨天天气好的话，我们就会去动物园了。3）错综时间条件句通常情况下，在非真实条件句中主句和从句的谓语动词所指时间是一致的，但有时也可能指不同的时间，这时要根据上下文的意思采用不同的谓语动词形式。即：有时if从句和主句所表示的假想情况时间不一致，如从句与现在事实相反，而主句表示与过去事实相反,那么句子两部分的动词形式应作相应的调整。You would be much better now if you had taken the doctors advice.If the weather had been more favorable, the crop would be growing still better.4) 含蓄条件句英语中某些假设的条件句不是通过if从句表达出来，而是包含在某些短语、上下文或其他方式中，其谓语也常用虚拟语气，我们称此种结构为含蓄条件句。主要有介词but for, without等。如：要不是有你帮忙，我们是不会成功的。If it hadnt been for your assistance we wouldnt have succeeded. =But for your assistance we wouldnt have succeeded.=Without your assistance we wouldnt have succeeded.Having known in time ,we might have prevented the accident.要是及时得知的话，我们也许能阻止这场事故。（-ing 分词做条件状语，暗示条件：If we had kown in time）Given more attention, the tree could have grown better.如果多留心的话，这树本来可以长的更好。(-ed 分词做条件状语，暗示: If the tree had been given more attention)I was too busy at that time, otherwise, I would have called you.我当时太忙，否则我就给你打电话了。（副词otherwise暗示条件）二、可以用在“(should)+动词原形”中的虚拟语气主要有以下几类：1) 用在 suggest, propose, arrange, plan, decide, advise, order, demand, request, desire, insist 等表示“建议”、“要求”、“命令”、“决定”、“安排”、“计划”、“主张”的动词后面接的宾语从句中。这里的 should 也可以省略。He suggested/ proposed/ demanded/ advised that they （should） read the rules carefully. 他建议/提议/要求/劝告他们要仔细阅读这些规则。2) 用在“It is desired/ suggested/ requested/ ordered/ proposed/ decided ”之后由 that 引导的主语从句中，should 也可以省略。It is requested that Miss Yang（should）give a performance at the part. 人们要求杨小姐在聚会上表演一个节目。3) 用在 suggestion, motion, proposal, order, plan, idea, advice, request, decision, requiry 等名词后面接的表语从句或同位语从句中，should 也可以省略。My idea/ motion/ advice/ is that we (should) do more eye exercises every day. 我的意见是我们每天应该多做眼保健操。4) 用在“It is / was necessary/ important/ strange/ incredible ”或“It is a pity/ a shame/ no wonder ”之后由 that 引导的主语从句中，should 有“应该”、“必须”、“竟然”、“居然”之意。It is necessary that he (should) be sent there at once. 有必要马上派他到那里去。It is strange that the wheel should turn so slowly. 真奇怪，这个轮子竟然转动得如此之慢。It is a great pity/ shame/ that he should be so conceited. 真遗憾，他竟会这样自高自大。三、其它形式的虚拟语气1) if only是“但愿”之意，引导的从句中的谓语动词要用虚拟语气，表示和事实相反的情况。If only I knew her name. 要是我知道她的名字就好了。(这是if only引导的从句，表达的是与事实相反的情况，所以谓语动词用虚拟语气，与事实相符的情况用know，与事实相反的情况用其过去式knew)If only he had remembered to send that letter. 要是他没有忘记寄那封信就好了。2）wish的用法 用于wish后面的从句，表示与事实相反的情况，或表示将来不太可能实现的愿望。其宾语从句的动词形式为： 真实状况 wish后从句动作先于主句动词动作用过去时或过去完成时，（be的过去式为 were） 从句动作与主句动作同时发生用现在时或过去时，将来不大可能实现的愿望用would/could +动词原形。I wish I were as tall as you. /He wished he hadnt said that. /I wish it would rain tomorrow.4) 用于“it is time+从句”中虚拟语气用于“It is(high, about)time+从句”这一结构中，从句谓语动词用过去式，表示早该做而仍未做的事。It is high time that we went back to college.5) 用于would rather等引起的从句中虚拟语气用于wouldhad rather(would prefer)引起的从句中，其谓语动词用过去式，表示当时或将来的情况；其谓语动词用“had+过去分词”，表示过去的情况。I would rather you didnt tell him anything about it.She would prefer that she had not stayed at home last night.高考链接1. (2008全国卷I) If the weather had been better, we could have had a picnic. But it _ all day.A. rained B. rains C. has rained D. is raining2. (2005江苏卷) Dont you think it necessary that he _ to Miami but to New York?I agree, but the problem is _ he has refused to. A. will not be sent; that B. not be sent; thatC. should not be sent; what D. should not send; what3. (2006湖北卷)_ fired, your health care and other benefits will not be immediately cut off. A. Would you be B. Should you beC. Could you be D. Might you be4.（2009福建卷）But for the help of my English teacher, I _ the first prize in the English Writing Competition. A. would not win B. would not have wonC. would win D. would have won 5.（2009天津卷）This printer is of good quality. If it _ break down within the first year, we would repair it at our expense. A. would B. should C. could D. might6.（2009浙江卷）The doctor recommended that you _ swim after eating a large meal.A. wouldnt B. couldnt C. neednt D. shouldnt 情态动词小练1. Why didnt Alex attend the party yesterday evening?He not have wanted to see me.A. should B. might C. could D. would2. Its very cloudy and freezing now.Yes, Im afraid it snowing tonight.A. must B. need C. shouldD. might3. Naturally, after I tell my brother what to do, he go and do the oppositeA. will B. may C. can D. must4. No driving after drinking is a rule that every driver obey in our country. A. will B. shall C. may D. can5. Can I pay the bill by check?Sorry, sir. But in our hotel payment be made in cash.A. need B. shallC. will D. can6. Why isnt Cathy here yet? She to be picked up at the station.A. could waitB. must waitC. might be waitingD. can be waiting 7. She just couldnt believe that her husband desert her after he became rich.A. mightB. must C. shouldD. shall8. Remind him that youre always there for him, this on purpose?A. should B. will C. does D. could9. We thought he would have won the game.What a pity! He too nervous when playing.A. had beenB. has beenC. wasD. would have been10. I saw Mr. Li at the meeting yesterday.Did you? H