1、专题十一 情态动词和虚拟语气考点1：情态动词一、情态动词的类型1.只作情态动词的有：must，can（could），may（might），ought to2.可作情态动词也可作实义动词的有：need，dare3.可作情态动词也可作助动词的有：shall（should）will（would）4.具有情态动词的某些特征的有：have（had）to，used to二、情态动词的特征1.有一定的词义，但不能单独作谓语，要和动词原形连用构成谓语。2.适用于主语的各种人称和数（have to例外，主语是第三人称单数时，要用has to）。例：We/He must work hard.我们/他一定要努力工作
2、。I have to walk home.我得步行回家。He has to walk home.他得步行回家。3.后面接动词原形He may lose his way.他可能会迷路。You ought to obey the law.你应该遵守法律。4.具有助动词的作用，即可用来构成否定句、疑问句及用于简略答语。例：I cant swim. Can you swim？No，I cant, either.我不会游泳，你会游泳吗？我也不会。三、情态动词的基本用法1.can & could1）can表示现在一般的能力，could表示过去一般的能力，即不表示做与未做某事例：Mary can speak
3、 three languages.玛丽能说三门语言。Tom could sing English songs at the age of 6.汤姆6岁就能唱英文歌了。2）表示请求、允许。在一般疑问句中，could可代替can，但比can语气更委婉，答语要用can例：Can/Could you help me?Yes, I can.你能帮我吗？可以。3）can表示具体事情发生的可能，常用于否定句、疑问句，表示疑惑、惊讶或不相信等语气。can表示理论上的可能时可用于肯定句。could表示推测时比can可能性小，可用于肯定句、否定句和疑问句。例：That cant be true.那不可能是真的。（
4、具体事情发生的可能，表示不相信）Accidents can happen in this weather.这种天气可能会发生事故。（理论上的可能性）It could be weeks before we get a reply.我们可能要等好几个星期才得到回复。4）用于固定句型中：canttoo/enough（无论也不为过）；cant help doing sth.禁不住做某事；cant help but do sth.不得不做某事；cannot/could not but do sth.不得不做某事。例：I cant thank him too much.我怎么感谢他也不为过。I could
5、 not but admire her.我不得不佩服她。2.may & might1）may表示请求或允许，意为：可以。might表示请求时语气更为委婉。might为may的过去式，常用于间接引语。例：You may leave the book where it was.你可以把书放在原来的位置。She said I might call her at the weekend.（间接引语）她说我可以周末给她打电话。2）may，might表示推测，用于肯定句，意为“可能；用于否定句，may not意为“可能不”，如表达“不可能”则用cant 。例：This coat may be Peters
6、.这件大衣可能是彼得的。This coat may not be Peters.这件大衣可能不是彼得的。3）may表示祝愿，其结构为：May+主语+动词原形。例：May you succeed！祝你成功！4）用于固定句型中：may/might as well do不妨，还是做 为好；may/might well+ do（=be very likely to do）很有可能做。例：So you might as well do what you love.所以你不妨做你喜欢的事情。Her appearance has changed so much that you might well not
7、 recognize her.她的模样变化如此大，你很有可能认不出她了。3.must1）表示必要性，意为：必须，其否定式为neednt/dont have to mustnt。例：Must I give up smoking？我必须戒烟吗？Yes，you must.是的，你必须。/No，you neednt/dont have to.不，你不必。2）表示：禁止，为may作“可以”讲时的否定式。例：You mustnt smoke here.你不可以在这里吸烟。3）表坚持，意为：偏要，非要。例：Must you make so much noise？你就非得弄出这么大声吗？4）表推断，用于肯定句
8、，意为：一定，准是。例：You must be tired after your long walk.你走了那么长的路后，一定累了。4.shall1）表示征求对方意见或请求，用于第一、三人称的疑问句中例：Shall I/he go to see you？我/他去看你，好吗？2）用于第二、三人称的陈述句中，表示说话者的意志，用来表达说话者给对方的命令、警告、允诺等。在条约、规定、法令等文件中表示义务或规定，意为“应该；必须”例：You shall have a new dress for your birthday.你过生日一定会有件新连衣裙。Each competitor shall wear
9、 a number.每个参赛者要戴一个号码。（规定）5.should1）=ought to，意为：应该。可表示义务上的“应该”，也可表示推测上的“按说应该”例：You should/ought to be listening.你应该听才对。（义务上的“应该）He should/ought to arrive by now.现在他按说应该到了。（推测上的“按说应该）2）表示说话人的惊讶、难以置信等情绪，意为：竟然例：Its strange that he should be late.真奇怪，他竟然会迟到。3）用作shall的过去式，置于I或we之后，表示打算或期望做的事例：We knew th
10、at we should be leaving the next day.我们知道我们第二天就要走。4）与表示命令、建议、请求、要求的动词或名词连用5）用于表示与将来事实相反的if从句中6.will & would1）用于各种人称，表示主语的意愿和意志例：He will take you home.他愿意送你回家。2）用于第二人称的一般疑问句，表示请求例：Will/Would you go with me？你愿意和我一起去吗？3）will用来叙述目前的习惯；would表示过去的习惯例：He would get up early when he lived in the country.他住在乡
11、下时总是早起。7.need & dare1）实义动词有人称和数的变化，可用于肯定句、否定句或疑问句中，构成否定句或疑问句时要用助动词do，does，did。例：2）情态动词没有人称和数的变化（dare可以有过去式dared），直接接动词原形，主要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。3）另外，dare作情态动词时，还可用于条件句中；作实义动词时，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，我认为练习：用所给动词的适当形式或用适当的情态动词填空1、Although you can （find）bargains in London，i
12、t is not generally a cheap place to shop2、Life is unpredictable; even the poorest become the richest.3、 I have a word with you？It wont take long.4、The rule states that no child be allowed out of the school during the day unless accompanied by an adult.答案：1、find2、may/might3、Can/May/Shall4、shall8.“情态动
13、词+have done”用法1）must have done 准是/一定做了否定式为：cant/couldnt+have done2）can/could have done本来能够做过去可能会做3）cannot/could have done过去不可能做过去没能够做4）may/might have done 也许/或许已经做了，一般只用于肯定句或否定句中（在否定句中表示“可能不），不用于疑问句，用might则表示语气更加弱5）should/ought to have done本该做而实际上未做6）should not/ought not to have done本不该做而做了7）neednt
14、have done本不必做而做了8）had better have done当时最好做了（其否定式had better not have done表达相反的含义）9）would like/love to have done过去愿意做但未做成10）would rather have done宁愿当时做了（其否定式would rather not have done表达相反含义，两者都表示“后悔之意）9.几组易混情态（助）动词1）would & used towould 表示过去反复的动作，常与every day，often frequently等连用例：When he was abroad，he
15、 would often read as many books as possible.在国外时，他总是尽可能多地读书。used to表示过去的状态、习惯，但现在已经不存在例：She doesnt get up so early as she used to.她不像以前那样起得那么早了。2）could & was able to & could have donecould 表示过去的能力，但不代表是否做例：He could ride a bicycle at the age of 5.五岁时他就会骑自行车了。was able to 表示过去有能力并且成功地做了，相当于managed to d
16、o sth.例：The fire spread very quickly but everyone was able to get out.火蔓延很快，但大家都成功地逃了出来。could have done 过去本有能力做某事，但没有做3）must & have tomust多表示由于主观需要或责任感而有必要、有义务去做某事，意为：必须例：I must clean the room because it is too dirty.由于房间太脏了我必须打扫。have to表示为客观条件、环境所迫而做某事，意为：不得不例：He has to leave school because he cant
17、 afford his schooling.因为他付不起学费，所以不得不辍学。4）didnt need to do & neednt have donedidnt need to do过去没必要做某事，不强调是否做例：I didnt get up that early yesterday，for I didnt need to.昨天我没那么早起床，因为没必要。neednt have done 过去没必要做某事，但做了例：I neednt have got up that early yesterday but I had to because the dog barked all the ti
18、me.昨天我本不必那么早起床，但是由于狗一直叫，所以我不得不起床。5）cant, wont, dont/doesntThe window wont open.这扇窗户怎么都打不开。（强调动作实施者执意要打开）The window cant open.这扇窗户打不开。（这扇窗户原来设计时就不能打开，是固定死的）The window doesnt open.这扇窗户开不开。（强调这扇窗户是坏的，存在质量问题）考点2：虚拟语气一、虚拟语气用于非真实条件句中从句谓语形式主句谓语形式例句与现在事实相反过去式（be动词用were）would/should/could/might动词原形If I were
19、you，I would seize the chance.如果我是你，我就会抓住这个机会。与过去事实相反had+过去式would/should/could/mighthave+过去分词If you had taken my advice，you wouldnt have failed.如果你听了我的建议，你就不会失败。与将来事实相反过去式should +动词原形were to+h词原形would/should/could/might动词原形If he shouldnt come tomorrow，we would put off the meeting.如果他明天不来，我们就推迟这个会议。使用
20、虚拟语气条件句时要注意的几点：1.当条件状语从句表示的行为和主句表示的行为所发生的时间不一致时，这种句子被称为“错综时间条件句，动词的形式要根据它所表示的时间做出相应的调整例：If you had followed my advice you would be better now.如果你听了我的建议，你现在就好一些了。（从句与过去事实相反，主句与现在事实相反）2.在if引导的非真实条件从句中，谓语动词含were，had，should，可将if省略，但需将were，had，should提到主语之前例：If I were at school again，I would study harder.
21、Were I at school again，I would study harder.如果我还有上学的机会，我会更加努力学习。3.有时假设的条件并不总是通过if引导的条件从句表达，而是隐含在某些词、短语或上下文中，此种句子为“含蓄条件句”，常见的词或短语有：without，in case，but for，for fear that，otherwise等例：Without your help，we couldnt have finished the work ahead of time.= But for your help，.=If it had not been for your help
22、，.=Had it not been for your help，.没有你的帮助，我们不可能提前完成这项工作。4.even if，even though也可用于虚拟语气，其引导的从句的形式与if从句在虚拟语气中的形式相同练习：If he (catch) the morning train, he wouldnt have been late for the meetingIf we (book) a table earlier, we wouldnt be standing here in the long queue.二、虚拟语气在wish, if only(=how I wish), as
23、 if后的从句中条件从句谓语形式例句从句谓语动作与主句谓语动作同时发生过去式（be动词用were）If only/How I wish I were a flying bird！我多希望我是一只会飞的鸟儿啊！He looks as if he were an artist.他看上去好像是名艺术家。从句谓语动作先于主句谓语动作发生had+过去分词If only I had seen the film！=How I wish I had seen the film！我要是看过那部电影该多好啊！She speaks English so fluently as if she had stayed i
24、n America for a long time.她说英语如此流利，好像她在美国待过很长时间似的。从句谓语动作后于主句谓语动作发生would+动词原形He learns English so hard as if he would go to the U.S.A.他如此努力学习英语，就好像他要去美国。注意：当句子所叙述的是真实的或极有可能发生的或存在的事实时，as if从句要用陈述语气。例：It seems as if it is going to rain.天似乎要下雨。He walks as if he is drunk.他走起路来像是醉了。练习：1、We wish we (can) f
25、ly into space by spacecraft one day.2、She works hard as if she never (know) fatigue.答案：1、could2、knew三、虚拟语气用在主句含“坚持、命令、建议、要求”的名词性从句类别名词性从句谓语动词形式例句一坚持：insistshould+动词原形（should可以省略）He suggested that we（should）start off early the next day.His suggestion was that we（should）start off early the next day.他建
26、议我们第二天早点出发。It was suggested that we（should）start off early the next day.人们建议我们第二天早点出发。二命令：order, command四建议：advise, suggest, propose, recommend四要求：require, request, demand, ask注意：suggest作“暗示，表明”讲，insist作“坚持说”讲，后面宾语从句的谓语动词不使用虚拟语气形式（should+动词原形），而使用陈述语气。例：The smile on his face suggested that he was sa
27、tisfied with our work.他脸上的微笑暗示着他对我们的工作很满意。The man insisted that he had never stolen the money.那个人坚持说他从来没有偷过钱。练习：用所给动词的适当形式填空1、He proposed that a referendum （hold）by December.2、He gave a proposal that the UN （set）up an emergency centre for the environment.答案：1.(should)be held2.(should)set四、虚拟语气用在“wou
28、ld rather+that从句”中条件从句谓语形式例句对现在或将来的虚拟过去式（be用were）Id rather they didnt hear of the news.我宁愿他们没有听到这个消息。对过去的虚拟had+过去分词Id rather I had not told him the bad news.我宁愿没有告诉过他那个坏消息。五、虚拟语气用在“It is(high)time+that从句”中that 从句谓语形式：过去式或should+动词原形，且should不能省略例句：It is（high）time that you went/should go to school.你们该
29、去上学了练习：1、It is high time that we (talk) about the problem.2、Id rather you (focus) more on your learning now.答案：1、talked/should talk2、focused六、虚拟语气用在“It is necessary等+that从句”中在“It is necessary/important/vital/surprising/strange/natural/a pity/essential等+that从句”中，that从句的谓语动词用should+动词原形，should可以省略。sho
30、uld表示感情色彩，意为：竟然。例：It is strange that the meeting（should）be put off till next week.那个会议竟然被推迟到下周，真奇怪。It is a pity that you（should）have to leave.真遗憾你非得走。七.虚拟语气用在目的状语从句中由in case，for fear that，in order that，so that等引导的目的状语从句，其谓语动词用could/should/might/would+动词原形”表示虚拟。例：They left early for fear that they would meet him.他们动身很早以免和他碰面。I gave you a map so that you wouldnt get lost！我怕你迷路，给过你一张地图！