高中英语情态动词和虚拟语气课件

1、高中英语情态动词和虚拟语气最新考点一：情态动词一、can， could与be able to1.表示能力(体力、知识、技能)。例：Can you lift this heavy box?(体力)Mary can speak three languages.(知识)Can you skate?(技能) 此时可用be able to代替。can只有一般现在时和一般过去式； 而be able to则有更多的时态。Ill not be able to come this afternoon.当表示“经过努力才得以做成功某事”时应用be able to， 不能用can。He was able to go

2、 to the party yesterday evening inspite of the heavy rain.知识精讲2.表示请求和允许。例：-Can I go now?-Yes， you can./No， you cant.此时可与may互换。在疑问句中还可用could， might代替， 不是过去式， 只是语气更委婉， 不能用于肯定句和答语中。例：-Could I come to see you tomorrow?-Yes， you can.(No， Im afraid not.)知识精讲3.表示客观可能性(客观原因形成的能力)。例：Theyve changed the timeta

3、ble， so we can go by bus instead. This hall can hold 500 people at least.知识精讲4.表示推测(惊讶、怀疑、不相信的态度)，用于疑问句、否定句和感叹句中。例：Can this be true?This cant be done by him.How can this be true?知识精讲【典型例题】1.(单项填空) In todays information age， the loss of data_cause serious problems for a company.2.(单项填空) Samuel， the t

4、allest boy in our class,_easily reach the books on the top shelf.知识精讲二、may， might1.表示请求和允许。might比may语气更委婉， 而不是过去式。否定回答时可用cant或must n*t， 表示“不可以， 禁止”。例：-Might/May I smoke in this room?-No， you mustnt.-May/Might I take this book out of the room?-Yes， you can.(No， you cant/mustnt.)知识精讲2.用于祈使句，表示祝愿。例：May

5、 you succeed!知识精讲典例剖析】You _ feel all the training a waste of time， but Im a hundred percent sure later youll be grateful you did it.知识精讲三、must，have to1.表示必须、必要。例：You must come in time.在回答引出的问句时， 如果是否定的， 不能用mustnt(禁止， 不准) ， 而用neednt， dont have to(不必)。例：-Must we hand in our exercise books today?-Yes，

6、you must/No， you dont have to/you neednt.知识精讲2.must是说话人的主观看法， 而have to则强调客观需要。must只有一般现在时， have to有更多的时态形式。例：I really must go now.I had to work when I was your age.知识精讲 3.must表示推测、可能性(只用于肯定的陈述句) 。例：Youre Toms good friend， so you must know what he likes best.Your mother must be waiting for you now.知识

7、精讲 【误区警示】1.must开头的疑问句， 其否定回答通常用dont have to或need nt。而不用must n。例：-Must I finish my homework first?我必须先完成作业吗?-No， you dont have to/need n*t.不，你不必。知识精讲 【误区警示】2.can和must在表推测时， can一般用于否定句中， 而must常用于肯定句中。例：It can not be LiLe i.那个人不可能是李磊。It must be LiLe i.那个人肯定是李磊。知识精讲 【典例剖析】1.-Cant you stay a little longe

8、r?-Its getting late， I really_go now， my daughter is home alone.2.You_be careful with the camera. It costs!知识精讲四、dare， need 1.dare作情态动词用时， 常用于疑问句、否定句和条件从句中， 过去式形式为dared，例：How dare you say Im unfair?He darent speak English before such a crowd， dare he?If we dared not go there that day， we couldnt get

9、 the beautiful flowers.知识精讲 2.need作情态动词用时， 常用于疑问句、否定句。在肯定句中一般用must， have to， ought to， should代替。例：You neednt come so early.-Need I finish the work today?-Yes， you must/No， you neednt.注意：dare和need作实义动词用时， 有人称、时态和数的变化。在肯定句中， dare后面常接带to的不定式。在疑问句和否定句中， dare后面可接带to或不带to的不定式。而need后面只能接带to的不定式。例：ld are to

10、 swim across this river.He doesnt dare(to) answer.He needs to finish his homework today.知识精讲五、shall， should 1.shall用于第一人称， 征求对方的意见。例：What shall we do this evening?知识精讲 2.shall用于第二、三人称， 表示说话人给对方的命令、警告、允诺或威胁。例：You shall fail if you dont work hard.(警告)He shall have the book when I finish it.(允诺)He shal

11、l be punished.(威胁)知识精讲3.should表示义务、职责等， 意为“应该”。例：You should be strict with yourself as an officer.作为一名官员，你应该严格要求自己。知识精讲六、will， would1.表示请求、建议等， would更委婉。例：Wil/Would you pass me the ball， please?知识精讲2.表示意志、愿望和决心。例：I wll never do that again.They asked him if he would goabroad.知识精讲3.would表示过去反复发生的动作或某种

12、倾向。would表示过去习惯时比used to正式， 且没有“现已无此习惯”的含义。例：During the vacation， he would visit me every other day.The wound would not heal.知识精讲【真题剖析】(短文改错) As the kid， I loved to watch cartoons， but no matter how many times I asked to watching them， my parents would not to let me.知识精讲七、should， ought to1.shoud， oug

13、ht to表示“应该”， ought to表示义务或责任， 比should语气重。例：I should help her because she is in trouble.You ought to take care of the baby.知识精讲2.表示劝告、建议和命令。should， ought to可通用， 但在疑问句中常用should。例：You should/ought to goto class right away.Should I open the window?知识精讲3.表示推测should， ought to(客观推测) ， must(主观推测) 。例：He must

14、 be home by now.(断定他已到家)He ought to/should be home by now.(不太肯定)This is where th coil must be.(直爽)This is where the oil ought to/should be.(含蓄)知识精讲考点二：情态动词+have done知识精讲 1.must have done表示对过去事情的肯定推测， 译成“一定做过某事”， 该结构只用于肯定句。例：It must have rained last night， for the ground is wet昨晚一定下雨了，因为地面还是湿的。You mu

15、st have been mad to speak to the servant.你和仆人说话，一定是发疯了。知识精讲 2.cant have done表示对过去事情的否定推测， 译成“不可能做过某事”，例：Mr Smith canth avc gone to Beijing， for I saw him in the library just now.史密斯先生不可能去北京了，我刚才还在图书馆见过他。Mary cant have stolen your money.She has gone home.玛丽不可能偷你的钱，她回家去了。知识精讲3.can have done表示对过去行为的怀疑，

16、 用于疑问句， 译成“可能做过吗?”例：There is no light in the room.Can they have gone out?屋里没有灯，他们可能出去了吗?There is nowhere to fnd them.Where can they have gone?到处找不到他们，他们可能到什么地方去呢?知识精讲4.could have done是虚拟语气， 表示对过去事情的假设， 意思是本来能够做某事而没有做。例：He could have passed the exam， but he was too car c less，本来他能够通过考试，但是他太粗心。知识精讲5.m

17、ay have done表示对发生过的事情的推测， 意思是“可能已经”或“也许已经”， 用于肯定句中。例：-What has happened to George?乔治发生了什么事?-I dont know. He may have got lost.我不知道，他可能迷路了。知识精讲6.might have done表示对过去事情的推测， might与may意思相同， 但可能性更小。多用于虚拟语气结构中。例：She might have achieved greater progress， if you had given her more chances.如果你多给她点机会，她可能已经取得了

18、更大的成绩。知识精讲7.would have done虚拟语气， 表示对过去事情的假设， 意思是“本来会”例：I would have told you all about the boys story， but you didntask me.我本来会告诉你这个小男孩的故事，但是你没有问我。知识精讲8.should have done“本来应该做某事， 而实际没做”， 含有指责对方或自责的含义。例：Tom， you are too lazy.The work should have been fi ished yesterday.汤姆，你太懒惰了，这项工作本来应该昨天就做完的。Look， T

19、om is crying.I should nt have been so harsh on him.看，汤姆哭了，我本不应该对他如此严厉的。知识精讲9.ought to have done表示过去应该做而实际并没有做，have done”用法基本一样。“理应做”， 往往表示遗憾。与“should例：I ought to have gone home last Sunday.我理应上星期日回家。You ought not to have given him more help.你不应该帮助他那么多。知识精讲10.need have done表示本来需要做某事而实际没有做。neednt have

20、 done则表示本来不需要做某事而实际做了。例：I neednt have bought so much wine-only five people came.我本来没有必要买这么多酒，只来了五个人。He need have hurried to the station.In that case， he wouldnt have missed the train.他本来需要快点去车站的，那样的话，他就不会误了火车。知识精讲【典例剖析】例：-Sorry， Mum! I failed the job interview again.-Oh， its too bad. You have made f

21、ull preparations.知识精讲考点三：虚拟语气一、虚拟语气在条件句中的应用包含条件从句的句子称为条件句。条件句分为两类：一类是真实条件句，一类是虚拟条件句。如果假设的情况很可能发生，就用真实条件句。例：If he has time， he will come，如果他有时间，他会来的。例：He wont succeed unless we plan well.他不会成功的，除非我们计划好。知识精讲如果假设的情况发生的可能性不大，则用虚拟条件句。虚拟条件句分为三种，见下表：例：If he had time now， he would/could/might go with you.要是

22、他现在有时间，他会和你一起去的。(与现在事实相反)例：If you had come a few minutes earlier， you would/could/might have met the famous singer.如果你早来几分钟，你就会见到那个著名歌手了。(与过去事实相反)例：If it were to snow this evening， they would not go out.如果今天晚上下雪，他们就不会出去。(与将来事实相反)知识精讲二、几种特殊的虚拟条件从句 1.省略if形式的虚拟语气在if虚拟条件句中， 若省略if， 则将should， were， had前置，

23、 构成主谓倒装句式。例：Had I worked harder， I would have succeeded.如果我当时努力学习的话，我就会成功的。Were she my daughter(Should she be my daughter) ， I wouldntallow her to study abroad.如果她是我的女儿的话，我就不让她出国学习了。知识精讲2.混合虚拟语气若主句和从句所表示的时间不一致，就构成了混合虚拟语气或错综虚拟语气，此时，主句和从句的时态形式根据实际的时间概念来定。例：If she had followed the doctorswords， she wou

24、ld feel better now.如果当初她听从了医生的建议，现在就会好多了。知识精讲3.含蓄虚拟语气有时候假设的条件不是通过条件从句表达， 而是隐含在某些介词短语中， 如without.， 连词but for，otherwise， or等中。例：Without music(=If the rc were no music) ， the world would be dull世界若无音乐将会很枯燥。Im really very busy， other wisc I would certainly go there with you.(other wisc=if I were not so

25、busy)我真的是太忙了，不然我就会同你一道去了。知识精讲三、虚拟语气在宾语从句中的应用1.动词wish后的宾语从句。表示现在的情况，从句谓语用过去式；表示过去的情况，从句谓语用过去完成式；表示将来的情况， 从句谓语用“would/should/could/might+动词原形。例：I wish I were ten years younger now.我希望我现在年轻十岁。I wish I had met him yesterday.我昨天能遇到他就好了。I wish I would be a scientist.我希望将来成为科学家。知识精讲【课堂演练】(单项填空) There is a good social life in the village, and I wish I_a second chance to become more involved.知识精讲 2.在表示请求、建议、命令、要求等动词后的宾语从句中， 谓语用“should+动词原形”， should可省略。常见的这类动词有：suggest， recommend， insist， order， require， advise， demand， command， ask， request，propose等。例：He suggested that we(sho