考点14 情态动词（原卷版）

2020年高考英语一轮考点扫描专题14 情态动词一、 【知识精讲】1. can/could（1）表示能力,意为“能,会”；could主要指过去的能力。She can run fast, but I cant.（2）表示可能性(理论上或是逻辑判断上),意为“可能会”。It is usually warm in winter in the south, but it can be cold and even have snow sometimes. （3）表示请求和允许,与may同义,常用于口语中。Can I have a look at that? （4）表示惊异、怀疑、不相信等态度时,主要用于否定句、疑问句或感叹句中,用could时语气较委婉。Where can/could he have gone?She cant/couldnt have left so soon.【易混辨析】can与be able to的区别（1） can只能用在一般现在时和一般过去时中,而be able to可用于更多的时态。He will be able to tell you the news soon.（2）表示过去特定的能力或经过努力才具备的能力,只能用be able to。I talked with her for a long time, and finally I was able to make her believe me.2. may/might（1）表示请求时,两者都可用,只是 might 表示的语气较委婉(但并不表示过去)；表示许可时,通常要用 may而不用might。Might I have a look at your new computer? 我可以看看你的新电脑吗？(表示请求)You may come in now. 你现在可以进来了。(表示许可)（2）表示推测,意为“可能,也许,指现在或将来的可能性,常用于肯定句和否定句。两者都可用,只是might比may语气更不确定,表示的可能性更小。He may be busy finishing his homework.【归纳拓展】（1）may well动词原形,表示“很可能”；may/might as well do不妨做某事。He may well be proud of his success.（2）may表示祝福与愿望,多用于书面语中,组成句型：Mayyou/n.动词原形. 。May you succeed. 祝您成功。3. must（1）表示现在或将来必须要做某事,多是出于义务、责任或强制命令,指说话人的主观意志。You must finish it today. （2）表示有把握的推测,只用于肯定句中,意为“一定,肯定”。He must be wrong. （3） must用于疑问句中,可以用来表示责备、抱怨的感情色彩,意为“偏要,硬要”。Must you interrupt now? Cant you see Im on the phone? 你非要现在打断我吗？难道你没看见我在打电话吗？【归纳拓展】（1）mustnt的意思是“禁止”,而不是“不必”。（2）have to表示“必须,不得不”,意义与must很接近,但must表示主观意志,而have to表示由于客观因素不得不做某事,并且可用于更多的时态。I told her that she must give up smoking.We will have to do it again.4. shall/should（1）shall用于第一、三人称的疑问句中时表示征求意见。 用于第二、三人称的陈述句时,往往表示给对方(you)或第三者(he, she, they)以允诺、命令、决心、警告或威胁等,在法律、条约、协定等文件中可以表示义务、规定等。Shall I get you some tea? 我给你倒点茶好吗？Each citizen shall carry his identification card when travelling. 旅游时每个市民务必带上身份证。(规定)（2）should表示劝告,意为“应该,应当”。You should help your mother with the housework.（3）should表示惊讶、赞叹或不满,意为“竟然”。Its strange that he should be late. 真奇怪,他竟会迟到。（4）should表推测,暗含很大的可能,意为“应该,可能”。Its 4：30. They should be in New York by now. 现在是四点半,他们应该到达纽约了。（5）用在if引导的条件状语从句中,表示可能性很少,但也不是完全不可能,意为“万一”。If it should rain tomorrow, dont expect me. 万一明天下雨,就不要等我了。5. will/would（1）will表示“意愿,意志”,would表示过去时间的“意愿、意志”。We will do our best to save the child.I told her to stop crying, but she just wouldnt listen.（2）“Will/Would you.？”表示请求或邀请,would的语气更委婉。有时也用“Wont you.？”意为“好吗？”“要不要”。（3）will表示某种倾向或习惯性动作,意为“总会,老是”；would表示过去反复发生的动作或过去的一种倾向。The door wont open. Every night he would come to say goodnight.【易混辨析】would与used to的区别（1）would表示过去经常性且反复发生的动作,没有与现在对比的含义。（2）used to表示过去经常发生的动作或存在的状态,且现在已终止,强调今昔对比。When we were boys, we used to/would go swimming every summer.People used to believe that the earth was flat. 过去,人们总以为地球是扁平的。(现在已不再这样认为)6. need, dare（1）need表示必要性,意为“需要”,dare表示“敢于”；need和dare作情态动词时常用于否定句、疑问句或条件句中,无人称和数的变化,疑问句和否定句中不加助动词。Need I telephone him now?She dare not go out alone at night.（2）need和dare用作实义动词时,有词形变化。在否定句、疑问句中要加助动词。You dont need to hurry. You have enough time.Does he dare speak to her? 【归纳拓展】（1） need作实义动词,后接动名词时,相当于动词不定式的被动形式。The old man needs looking after/to be looked after. （2）I dare say表示“我以为,我想”。She is not here yet, but I dare say she will come later.7. ought to（1）ought to与should意思大体相同,但ought to语气比should重,往往表示从法律或道义上“应该”。You are his father and ought to take care of him.你是他父亲,应当照顾他。(有责任,从道义上应该)（2）should表示推测时,表示确定或可能性大的期望,语气较强。That should be Janet coming upstairs now.8. “情态动词have done”的用法（1）must have done表示对过去已发生的事情进行肯定的推断,只用于肯定句中,意为“一定,肯定”,其否定形式为：cant/cannot have done。It must have rained last night, for the road was quite wet. 昨晚肯定下雨了,因为路面十分潮湿。（2）could have done意为“本来可以,本来能够”,表示虚拟语气。You could have made greater progress, but you didnt try your best.（3）may/might have done表示对过去已发生的事情进行推断,意为“可能/或许已经”。其否定形式为：may/might not have done,意为“可能没有做”。To be frank with you, I may have made a mistake.（4）should/ought to have done表示“本应该做某事,却没有做”,含有责备或后悔之意。其否定形式为should not/ought not to have done,表示“本不该做某事却做了”。You ought not to have made fun of him. He is not the one you laugh at but learn from.（5）neednt have done表示“本没有必要做某事却做了”,多用于否定句中。You neednt have waken me up; I dont have to go to work today. 注意：neednt do表示“没有必要去做某事”,时间上应该是现在或将来。You neednt telephone him now, for he isnt at home. 你现在不必打电话给他,因为他不在家。二、 【典例精练】1. In todays information age, the loss of data _ cause serious problems for a company.2. “Each director _be appointed or recalled by his own side,” the judge declared in the court.3. Instead of making choices for their children, liberal parents usually say, “Go where you _.”4. The painting _not be a masterpiece, but the colors are marvelous.5. Samuel, the tallest boy in our class, _easily reach the books on the top shelf.6. My room is a mess, but I _clean it before I go out tonight. I can do it in the morning.7. It was sad to me that they, so poor themselves, _ bring me food.8. Days later, my brother called to say he was all right, but _ say where he was.9. I_ thank you too much for all your help to my son while we were away from home.10. One of our rules is that every student _ wear school uniform while at school.知识改变命运7