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1、高考英语微专题 二轮复习讲义高中英语语法情态动词(must can may have to)用法考点总结 讲义(上)(1)情态动词主要用于表明说话者对某一行为的态度和观点,包括能力、可能、义务、必要、猜测、责备等情态动词是“辅助性”动词,不能独立使用,必须和动词原形一起构成谓语情态动词没有人称和数的变化,但是有时态的变化,其中“情态动词+have+过去分词”结构为考察重点。Can, be able to和could的用法Can 和be able to均为“能、会”,表示能力时可相互转换,can常用于一般现在时,而将来时和完成时常用be able toCan you play the violi
2、n?= Are you able to play the violin?你会拉小提琴吗?Well be able to get you a job soon.我们很快就可以给你提供一份工作。He has been able to finish the work on time.他已经能按时完成工作了。注意:could是can的过去式,可用于一般过去时和完成时“could have +过去分词”表示“过去本能做某事却没做”,是一种虚拟语气的表述。其否定形式为“couldnt have+过去分词”则只能表示对过去已经发生事情的否定推测,相当于“cant have+过去分词”,意为“不可能”,“不会
3、”But we could have done it much better.但是我们本来可以做得更好。(事实并非如此)John could have been seriously hurt in the accident.约翰可能在那次事故中受了重伤。(过去可能)考点练习I my examination easily but I made too many stupid mistakes.A.must pass B. must have passedC. would pass D. could have passed答案及解析:D 根据句意即but后面分句中的过去式台克制,前面的分居时对过去
4、事情的推测,所以应该用“情态动词+have +过去分词”的形式,排除A、C。“must have+过去分词”表示“一定做了”,是对过去事情的肯定推测,“could+ have +过去分词”表示“过去本可以做而没有做”,根据句意选D(2)“may/might have+ 过去分词”表示对过去发生事情的可能性的推测,might比may更含蓄和委婉。may表示允许、请求或可能性用may提问时,肯定回答一般用Certainly或Yes, you may.否定回答一般用cant或mustnt.They may have called while you were out.你出去时他们可能给你打过电话。M
5、ay I ask you a question?Certainly.可以问你一个问题吗?当然可以。It may be in your pocket.它可能在你的衣袋里。The man might have been fired if he had not made an apology to his boss.如果没有向老板道歉的话,那个人也许被开除了。考点练习He stupid things, but we respect him just the same.A.should do B. would have doneC.may have done D. must do答案及解析:C 他可能
6、做过蠢事,但我们依然尊敬他。根据句意可知,前面的分居时对过去发生事情可能性的推测,而“may/might have+ 过去分词”正是表示对过去发生事情可能性的推测,意为“可能已经做过.”。(3)must和have to 的用法must表示“必须”、“一定”的意思表示“必须”时否定形式是mustnt表示“一定”时,否定形式是“cant”We must be very careful when we cross the road.我们过马路时一定要非常小心。It must be Jack.那准是杰克。I havent seen Kate today. She cant be here我今天没有看到
7、过凯特,她不可能在这里)。注意用must(必须)进行提问时肯定回答用must,否定回答用needntMust we clean the room before we leave?Yes,you must./No,you neednt.我们走之前必须要打扫房间吗?是的,必须打扫。/ 不,不需要。用must(一定)进行提问时肯定回答仍用must,但是否定回答用cant.Must she be in the romm?Yes,she must./No,she cant.她一定在房间里吗?是的,一定。/ 不,不可能在。“have to”表示“不得不”、“必须”。Well have to leave n
8、ow for it is very late at night.我们现在必须离开了,因为已经很晚了。have to疑问形式是:助动词+have to否定形式是:助动词+not+have to/neednt.Do you have to stay until 8 oclock?你得呆到8点钟吗?You dont have to do so.(=You neednt do so.)你不用这么做。考点练习From what you said, she you all about it.A.must tell B. must be tellingC. tells D. must have told(4
9、)“must+ have+过去分词”表示对过去情况的肯定推测,意为“肯定做了”.其否定式为“cant/couldnt have+过去分词”,表示“不可能做过”或者“不可能发生”,不存在“mustnt have+过去分词”这一形式。You must have gone to bed late last night,for your eyes are red.你昨晚一定睡得很晚,因为你的眼睛已经很红了。Mary cant have appeared in the office, because she has already gone home.玛丽不可能出现在办公室,因为她已经回家去了。“sho
10、uld/ought to have +过去分词”表示与过去事实相反的情况,表示“本应该做某事而没有做”,其否定式为“shouldnt/oughtnt have+过去分词”,表示“本不应该做某事却做了”。You shouldnt have been following him so closely; you should have kept your distance.你本不该一直这样紧跟着他,你本应该保持距离的。You ought to have told him that the paint on that seat was wet.你本应该告诉他座位上的油漆还没有干。You oughtnt
11、 to have given him more help.你本不应该给他更多帮助的。考点练习I regret having left the work unfinished; I_ everything ahead carefully.A. should have planned B. must have plannedC. might have planned D. could have planned答案及解析:A 我后悔没有完成这样工作,我本应该提前仔细计划好一切的。“should + have+过去分词”表示与过去事实相反的假设,意为“本应该做某事而没有做”;“must + have+过去分词”表示对过去情况的肯定推测,意为“肯定做了某事”;“might+ have+过去分词”表示对过去情况可能性的推测,意为“可能做了某事”;“could have+过去分词”表示与过去事实相反的假设,意为“本可以做某事而没有做”。学科网(北京)股份有限公司