1、高考英语专题七 情态动词与虚拟语气专题七情态动词与虚拟语气情态动词的基本用法情态动词具有一定的词义，没有人称和数的变化，必须和其他动词一起构成谓语，用来表示愿望、态度或推测等。1表示能力(1)表示现在的能力(2)表示将来的能力：will be able to(3)表示过去的能力I cant promise anything, but Ill do what I can.我不能许诺什么，但我会尽力而为。(表示现在的能力)The fire spread through the hotel very quickly but everyone was able to get out.尽管这场大火迅速蔓
2、延到了这个宾馆，但是每个人都逃了出去。(表示过去有能力做并且成功地做了)I could have worked out the problem, but I was too nervous.我本来可以解出这道题，但我太紧张了。(表示本来有能力做但未做)2表示推测(可能性)可能性可分为客观的可能性和具体事情实际发生的可能性两种。(1)客观的可能性并不表示具体某事是否会发生，而用来说明人或事物的特征。情态动词can可用于肯定句中表示客观的(或理论的)可能性，而表示具体事情实际发生的可能性时， can一般不用于肯定句。Accidents can happen on such rainy days.在
3、这样的多雨天气里可能会发生事故。(表示客观的可能性)We may go to the cinema tonight, but we are not sure yet.今晚我们可能去看电影，但还没确定。(表示实际可能性，不用can)(2)表示具体事情实际发生的可能性表示具体事情实际发生的可能性的层次(由强及弱)比较：词形肯定式否定式疑问式must 必定，必然/should按说应该应该不会/ought to按说应该应该不会/can/不可能有可能吗？could微弱的可能不可能语气比can弱may或许，也许，也说不定可能不/might比may还弱比may not还弱/在肯定句中表示推测(must/ha
4、ve to, should/ought to, may, might, could)a当说话者表达怀疑或犹豫之意时，需用may, might或 could, 其中might, could比may所表达的怀疑或犹豫之意更强。That may be our taxi now!现在那辆可能就是我们的出租车了！That could/might be our taxi (but I doubt it)那辆有可能是我们的出租车(但我有所怀疑)。b当说话者表达毫无疑问的结论时，需用must和have to (较通俗)，意为“一定，肯定”；should和ought to所表达的程度不如must强，但比may,
5、 might和could强，should/ought to表示推测出合乎理想的情况或结果，意为“按说应该”。He must/has to be the wanted man: Hes exactly like the one in this picture. 他一定是被通缉的那个男子：他和这张照片上的人一模一样。He ought to/should be here on time he started early enough.他应该按时到这里他出发得够早的。在否定句中表示推测(may not, might not, shouldnt, cant, couldnt)否定语气较弱时，常用shou
6、ld not (应该不会)，或用may not, might not (可能不，也许不)；否定语气较强时，则用cant或couldnt (不可能)。Dont worry. Your father may not have been hurt seriously.别担心，你父亲也许伤得不厉害。There shouldnt be any difficulty in getting you a visa.给你弄个签证应该不会有什么困难。在疑问句中表示推测(can, could)can, could在疑问句中，常表示困惑、不相信等。Theres someone outside who can it b
7、e?外面有人会是谁呢？What can they be doing?他们可能在干些什么呢？Could he be serious?他是当真的吗？Where can she have put it?她能把它放在哪儿呢？3表示必要性、义务、责任(1)表示必要性You neednt have worked that late last night. It was harmful to your health.你昨晚本来不必工作到那么晚的。那对你的健康有害。Must I give up smoking?Yes, you must. /No, you neednt.我必须戒烟吗？是的，你必须。/不，你不
8、必。(2)表示义务、责任should意为“(义务上)应该”，在语气上比must (必须)弱。“should动词原形”表示现在或将来应该；“shouldhave过去分词”表示过去本该。I should go and visit him this afternoon, but I wonder if I will be free.今天下午我应该去看望他，但我不知道我是否有空。(表示将来应该)You should have come to the conference yesterday. What was the reason for your absence?你昨天本应该参加那个会议。你缺席的原
9、因是什么？(表示过去本该)4表示请求、建议、命令、允许、禁止(1)表示请求、建议表示请求许可或提出建议时用：May I sit down？我可以坐下吗？No, you mustnt.不，你不可以。Shall the driver wait outside?司机在外边等着可以吗？Would you do me a favor?请帮我一下，好吗？名师指津请求对方许可时，could表示委婉的语气，回答时要用can。Could I use your bike tomorrow morning?Yes, you can.(否定：No, Im afraid not.)明天早晨我用一下你的自行车，行吗？行，
10、你用吧。(否定：不，恐怕不行。)主动提出帮忙时用：Shall I/we .?Whats your name?Aaron. Shall I spell it for you?你叫什么？Aaron。我为你拼出来好吗？(2)表示命令、允许、禁止must (必须), mustnt (禁止)可以表示说话者的命令或指令，语气比较强烈；should/ought to(应该), shouldnt/oughtnt to (不应该)也可表示说话者的命令、指令，但暗含对对方是否听从并无把握；may/might, can 表示允许。The children must be back by 4 oclock.孩子们必须
11、在4点钟以前回来。You mustnt leave the gate open.你不要让大门敞开着。You ought to/should apologize.你应该道歉(虽然我不知道你是否会这样做)。You oughtnt to/shouldnt neglect the garden.你不应该疏于照管花园。You may/can/might come if you wish.你想来就来吧。Passengers may/can/might cross by the footbridge.乘客可通过步行桥穿过去。5表示意愿、意志、决心、允诺(1)shall与第二、三人称连用，用于陈述句中，表示说
12、话者的意志，用来表达说话者给对方以命令、指示或允诺。此外，当宣布法律、规定时，也用shall来表达。It has been announced that candidates shall remain in their seats until all the papers have been collected.已宣布，在所有试卷收上来之前，应试者必须留在自己的座位上。(规则或规定)(2)will, would与各种人称连用，用于陈述句，表示主语的意愿、意志或决心。You can stay here as long as you can, if you will.如果你愿意，你想在这里待多长时
13、间就待多长时间。(表示主语的意愿)Mr. Gordon asked me to remind you of the meeting this afternoon. Dont you forget it!OK, I wont.戈登先生让我提醒你今天下午有会议。你可别忘了！好的，我不会忘的。(表示决心)6表示习惯和倾向will (wont)可用来叙述真理，还可叙述目前的习惯，would (wouldnt)可以用来叙述过去的习惯。Engines wont run without lubricant.没有润滑剂发动机就不能运转。She will listen to records alone in h
14、er room for hours.她独自一人在屋里听唱片，常常一听就是几个小时。He would spend hours in the bathroom or on the telephone.他以前一进洗澡间或是一打电话，往往就是几个小时。名师指津would和used to都可表示过去的习惯，但前者表示过去反复的动作，常与every day, often, frequently等连用；后者表示过去的状态或过去的习惯，但现在已不存在。When he was abroad, he would read as many books as possible.在国外时，他总是尽可能多读书。She d
15、oesnt get up so early as she used to.她不像以前那样起得那么早了。7need和dare的用法作实义动词有人称和数的变化后接to do用于肯定句、否定句、疑问句构成否定句、疑问句时要用助动词作情态动词无人称和数的变化后接动词原形多用于否定句与疑问句构成否定句、疑问句时不用助动词He neednt do it.(情态动词)He doesnt need to do it.(实义动词)他不必做这件事。I didnt know whether he dared say that to him.(情态动词，有时态变化)我不知道他是否敢对他说那些。名师指津(1)dare作
16、情态动词时，还可用于条件状语从句中，过去式为dared；(2)作实义动词时，dare用于疑问句或否定句，后面的to也可省略；(3)I dare say是习惯说法，意为“我想，大概”；(4)need作实义动词时，还可表示“需要”，后接动名词的主动形式或不定式的被动形式表示被动含义。He didnt dare (to) do it.(实义动词)He dared not do it.(情态动词)他不敢那么做。命题点感悟 单句语法填空(2017北京高考改编)Samuel, the tallest boy in our class，_ easily reach the books on the top
17、shelf.解析：can句意：塞缪尔，我们班最高的男孩，能轻松地够到书架顶层上的书本。can表示“能够”。(2016浙江高考)Then he and my mother _ (have) a drink while she prepared dinner and they would talk about his day and hers.解析：would have根据语境可知，此处描述的是过去的一种习惯，故用would do表示“过去常常做”。(2015全国卷)We _ find ways to protect our environment.解析：must情态动词must表示“必须”，强调
18、主观上。情态动词have done1对过去发生的事情或状态进行推测must have done sth.“(过去)一定做了某事”；语气比较肯定；用于肯定句may (might) have done sth.“(过去)可能/也许做了某事”；语气不确定；用于肯定句和否定句can (could) have done sth.“本能够做某事”；用于否定句和疑问句，表示对过去发生的行为的怀疑或不确定Looking at the large empty apartment, I began aware of how lonely my mother must have been in Brazil her
19、self.看着这个又大又空的公寓，我开始理解妈妈独自一人在巴西一定也很孤单。The boy might have known the truth, but I am not quite sure.那个男孩也许知道了真相，但我不是很确定。I didnt see her in the meeting room this morning. She couldnt have spoken at the meeting.我今天上午在会议室时没看见她，她不可能在会议上讲话。2表示“与过去事实相反”could have done sth.过去本可以做某事但实际上没做neednt have done sth.
20、过去本不必做某事但实际上做了ought to/should have done sth.过去本应该做某事但实际上没做oughtnt to/shouldnt have done sth.过去本不应该做某事但实际上做了might have done sth.过去可能做某事但实际上没做He could have gone on regretting it, as too many of us do.他本可以继续为此而遗憾，正如我们中很多人一样。I neednt have taken the umbrella, for the weather is fine.天气这么好，我本没必要带雨伞的。You o
21、ught to have done this exercise more carefully.你本应该更仔细地做这个练习。You might have given him more help, though you were busy.你本可以给他更多帮助，虽然你当时很忙。命题点感悟 单句语法填空(2015天津高考改编)I neednt _ (worry) before I came to the new school, for my classmates here are very friendly to me.解析：have worriedneednt have done表示“本没有必要做
22、”。(2013浙江高考改编)I _ (enjoy) myself more it was a perfect day.解析：couldnt/cant have enjoyed句意：我玩得再开心不过了这是完美的一天。“cant/couldnt . more”表示最高级的意思；根据题干中的was可知设空处表示“对过去发生的事情的态度”，故答案为couldnt/cant have enjoyed。(2013全国卷改编) Since nobody gave him any help, he _ have done the research on his own.解析：must句意：既然没有人帮助他，他
23、一定是独自完成了这项研究。根据题干中“Since nobody gave him any help”可判断设空处表示肯定的推测。虚拟语气1虚拟语气用于条件状语从句中(1)虚拟语气在非真实条件句中的运用类别从句谓语动词主句谓语动词与现在事实相反过去式(be用were)should/would/could/might动词原形与过去事实相反had过去分词should/would/could/mighthave过去分词与将来事实相反过去式(be用were)should/would/could/might动词原形should动词原形were to动词原形If my brother were here,
24、everything would be all right.要是我哥哥在这儿的话，一切都没问题了。If it should rain this afternoon, the basketball match would be put off.要是今天下午下雨，篮球比赛就会被推迟。If you had taken my advice, you would not have failed in the exams.如果你早听了我的建议，你考试就能通过了。(2)虚拟条件句中的省略与倒装如果虚拟条件句中含有were/had/should，有时可把if省略，把were/had/should提到主语之前形
25、成倒装；若为否定形式，not不可提前。Had he caught the morning train, he would not have been late for the meeting.要是他赶上了早晨的火车，那他就不会开会迟到了。(3)错综时间条件句有时条件句的动作与主句动作发生的时间不一致，这时动词的形式应根据它们各自表示的时间加以调整。If we had booked a table earlier, we wouldnt be standing here in a queue.如果我们早些订位子，现在也就不用站在这里排队了。(if条件句是对过去的虚拟，而主句是对现在的虚拟。)(4
26、)含蓄条件句有时假设的情况不用条件句表达，而是用but for, without等介词(短语)或上下文来表示。We wouldnt have finished the project on time without your timely help.如果没有你的及时帮助，我们就不能按时完成那项工程了。用连词otherwise, or等暗示后文与前面的情况相反，从而引出后文的虚拟语气。I was ill that day. Otherwise, I would have taken part in the sports meeting.我那天病了，否则，我就参加运动会了。虚拟条件通过but暗示出
27、来，模式为“虚拟情况but真实情况”。I would have delivered a speech, but I had a cold that day.我本来可以做演讲，但是那天我感冒了。2虚拟语气用于名词性从句中(1)在“It isimportant/necessary/natural/strange/essential/vital/a pitythat . ”句型中，that从句中谓语动词用“(should)动词原形”。Its vital that we (should) take our safety driving along the road seriously.认真对待我们在路
28、上开车时的安全非常重要。(2)在would rather (that)后的宾语从句中，从句的谓语动词如果表示现在或将来要发生的动作，从句用一般过去时；如果表示过去发生的动作，从句用过去完成时。Id rather he had gone to the seaside with me the day before yesterday.要是他前天和我去海边就好了。(3)句中含有以下单词或变形时，该句中的名词性从句(宾语从句、表语从句、主语从句、同位语从句)部分常用虚拟语气，其谓语动词形式为“should动词原形”，其中should可以省略。He suggested that we (should)
29、start off early the next day.他建议我们第二天早点出发。名师指津当suggest表示“暗示，表明”之意，insist表示“坚持说”之意时，suggest/insist后的宾语从句不使用虚拟语气，而使用陈述语气。The smile on his face suggested that he was satisfied with our work.他脸上的微笑表明他对我们的工作很满意。The man insisted that he had never stolen the money.那个人坚持说他从没有偷过那笔钱。(4)wish后宾语从句中的虚拟语气虚拟语气从句谓语
30、动词与现在事实相反过去式(be动词一般用were)与过去事实相反had过去分词与将来事实相反would/could动词原形I wish (that) I were ten years younger.但愿我能年轻十岁。I wish (that) I had met that film star yesterday.我多希望昨天见到了那个影星。(5)as if/though引导的表语从句和方式状语从句中的虚拟语气as if/though引导的从句中的谓语动词形式及使用情况与wish后宾语从句中的谓语动词及使用情况相同。She looks as if nothing had happened to her.她看起来好像什么事都没有发生似的。名师指津如果从句中描述的事情可能会发生，那么从句中的谓语动词可用陈述语气。It sounds as if it is raining.听起来像是在下
