2017届高考英语牛津版一轮复习语法考点专练课件：9 情态动词和虚拟语气_高考复习指南

2017届高考英语牛津版一轮复习语法考点专练课件：9 情态动词和虚拟语气

　　虚拟语气是用来表示与现在或过去的实际情况相反的假设,近年来主要是考查上述两点,而对将来可能情况的假设已很少涉及。注意下列几种情况: 1.表示与现在实际情况相反的假设:条件从句谓语动词应该用一般过去时(be 动词用were),主句谓语动词要用should/might/would/could+动词原形。 2.表示与过去实际情况相反的假设:条件从句谓语动词应该用过去完成时,主句谓语动词要用should/might/would/could have done。 3.用其他形式来代替条件从句,常见的有:without,otherwise,but for等。 4.一些特殊动词后的that从句中谓语动词要用(should+)动词原形,常常考查把 should去掉的情况。与这些特殊动词相关的名词形式后的that引导的同位语从句的谓语动词也符合这一原则。 5.需要特别注意的几个结构:wish句式,as if/though句式,would rather...,It's high time...等。典例6 (2015北京,34)If I (see)it with my own eyes,I wouldn't have be- lieved it. 答案　hadn't seen 解析　句意:如果不是我亲眼看到,我是不会相信的。由主句谓语“wouldn't

　　have believed”可知此处为与过去事实相反的假设,故if从句谓语动词应为 hadn't seen。知识清单一　情态动词的用法要点一、表能力如: I am starving to death.I can eat two bowls of rice now.(现在的能力) 我快饿死了,现在我能吃两碗米饭。 If you have a good sleep,you will be able to work out this problem.(将来的能力) 知识清单如果你好好睡一觉,你将能够解出这道题。 The fire spread through the hotel very quickly but everyone was able to get out. (过去有能力做并且成功地做了某事) 尽管这场大火迅速蔓延到了整个宾馆,但是每个人都逃了出去。 I could have worked out the problem,but I was too nervous.(过去有能力做但未做) 我本来可以解出这道题,但我太紧张了。 1.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。所谓客观的(理论的)可能性即并不涉及具体某事是否会发生,此种用法常常可以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(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。如: Accidents can happen on such rainy days. 在这样的多雨天里可能会发生事故。(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。(实际可能性,不用can) 2.表示具体事情实际发生的可能性: (1)表示具体事情实际发生的可能性的层次比较(见下表) 二、表推测(可能性) 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,也未可知,也说不定可能不 / might 比may还弱比may not 还弱 / (2)表示具体事情实际发生的可能性时,may,must常用于肯定句,一般不用于否定句和疑问句(may not表示“可能不”);can 常用于否定句、疑问句或感叹句中,表示疑惑、惊讶或不相信等意思;could既可用于肯定句又可用于否定句、疑问句中。如: This can't/couldn't be done by him. 这不可能是他干的。(表不相信) This may not be done by him. 这可能不是他干的。(表不确定) He could be on his way home now. 他现在可能在回家的路上了。(could 不如may/might常用) Can this be done by him? 这可能是他干的吗?(表示疑惑、惊讶) Mr.Bush is on time for everything.How can it be that he was late for the opening ceremony? 布什先生做一切事情都非常守时。开幕式他怎么可能会迟到呢?(表示疑惑、惊讶) I didn't hear the phone.I must have been asleep. 我没听见电话铃响。我一定是睡着了。(表肯定) —Are you coming to Jeff's party? —I'm not sure.I might go to the concert instead.(表不确定) ——你要来杰夫的聚会吗? ——我不确定。我可能要去音乐会。 (3)could,might并不一定与过去的时间有关,而表示可能性弱于它们相应的现在时形式。如: This may/might be done by him. 这件事有可能是他干的。(语气依次递减) (4)should表推测时,表示确定或可能有的未来或期望,即合乎理想的情况或结果。如: He ought to/should be here on time—he started early enough. 他(应)该按时到这里——他出发得够早的了。 We should arrive before dark. 我们按说能在天黑前到达。 The roads should be less crowded today. 按说今天路上就不那么拥挤了。三、表示请求、允许、允诺 1.当对方是决策者时,你代表你(们)自己(I,we),或代表第三者(he,she,they)向对方(you)请示或提出建议时用:①Shall/May(Might)/Can(Could)I/we...?②Shall he /she/they...?③Would/Will you...?如: Shall the driver wait outside? 司机在外边等着可以吗? When shall my father be able to leave hospital? 我父亲什么时候可以出院? Would you do me a favor? 请帮我一下,好吗? 2.could/might/would/should表委婉的语气。如: —Could/Might I use your bike tomorrow morning? —Yes,you can/may.(否定:No,I'm afraid not.) ——明天早晨我用一下你的自行车,行吗? ——行,你用吧。(否定:不,恐怕不行。) 不可以说:Yes,you could/might.回答允许时,用could/might表委婉是不恰当的。 3.shall与第二、三人称连用,用于陈述句,表示说话者的命令、警告、威胁;当宣布法律规定时,也用shall。 You shall leave the room at once,and he also shall.(=I order you and him to leave the room at once.) 你马上离开这个房间,他也一样。(说话者的命令) It has been announced that candidates shall remain in their seats until all the pa- pers have been collected. 据宣布,在所有试卷收上来之前,应试者必须待在自己的座位上。(规则或规定) 四、表示必要性 1.must 常用来表示必要性,意为“必须”,must do sth.(现在或将来)必须做某事。 2.don't have to do sth./don't need to do sth./needn't do sth.(现在或将来)不必做某事。 3.表示过去没必要做某事时,分为以下情况: (1)needn't have done sth.本来不必做而做了某事 (2)didn't have to do sth./didn't need to do sth./It was not necessary to do sth.(过去)不必做(不强调是否做了)某事 You needn't have worked that late last night.It was harmful to your health. 你昨晚本不必工作到那么晚。那对你的身体没好处。 —Did you work very late last night? —No,I didn't.I didn't need to work very late. ——你昨天晚上工作到很晚吗? ——不是很晚。我没必要工作到很晚。 4.should也可以表示必要性,意为“(义务上)应该”。should表示必要性时,在语气上比must(必须)弱。“should+动词原形”表示现在或将来应该做(的必要性);“should+have+过去分词”表示过去本该做(的必要性)。如: 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。(表示将来的必要性) 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。你缺席的原因是什么?(表示过去的必要性) 五、表示“宁愿做某事”时,可使用下面这些句式: 高考中对这类用法的考查主要侧重结构,因此要熟记其结构。情态动词+have done 用法例句 must have done 想必/准是/一定做了否定式为:can't/couldn't+have done It must have rained last night,for the road is quite muddy.昨晚一定下雨了,因为路很泥泞。 can/could have done 1.本来能够做 2.过去可能会做 Can he have gone to his aunt's? 他有可能去他姨妈家了吗? cannot/could not have done 1.过去不可能 2.过去没能够 He cannot have forgotten it. 他不可能忘了那件事。六、“情态动词+have done”用法一览表 may/might have done 也许/或许已经做……,一般只用于肯定句或否定句中(在否定句中表示“可能不”),不用于疑问句中。might则表示语气更加不肯定。 It's too late.I think he may have gone to bed.太晚了,我想他或许已经睡了。 He may not have finished the work.他也许还没完成那项工。 should/ought to have done 本该做而实际上未做 You ought to have done this exercise more carefully.你本应该更仔细地做这个练习。 should not/ought not to have done 本不该做而做了 You shouldn't have told her the truth. 你本不该告诉她真相。 needn't have done 本不必做而做了 You needn't have taken a taxi here,for it was very near to my house.你本来不必打车来这里的,因为离我家很近。 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) You had better not have scold- ed her. 要是那时你没责骂她就好了。 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,两者都有“后悔”之意) I raised objections at the meet- ing,but now I would rather not have done that. 我在会上提出了反对意见,但现在我宁愿没那么做。 would like/love to have done sth. 过去愿意做但未做成 I would love to have gone to the party last night,but I had to work extra hours to finish a re- port. 昨晚我本来很想去参加聚会的,但我得加班完成一个报告。七、情态动词的其他用法要点: 1.cannot but+do sth.表示“不得不,只好做某事”。如: I cannot but choose to go.我只好去。 2.may well和may as well结构。 “may well+动词原形”是一种常用结构,意为“完全能,很可能”,相当于“be very likely to+动词原形”。如: He may well be proud of his son. 他大可为他的儿子感到自豪。 Her appearance has changed so much that you may well not recognize her. 她的模样变化太大,你很可能认不出她了。 “may as well+动词原形”意为“最好,不妨,倒不如”。如: You may as well do it at once.你最好马上就做这件事。 We may as well stay where we are. 我们留在现在的地方倒也不错。 3.cannot(或can never)与enough连用表示“再……也不为过”。(具体用法见形容词和副词专题。) 4.may可以用于祈使句,表示祝愿。如: May we never forget each other.愿我们彼此永不相忘。 May you return in safety.愿你平安归来。 5.“Why/How+should”结构表示说话人对某事不能理解,感到意外、惊讶等, 意为“竟会”。如: Why should you be so late today?你今天怎么来得这么晚? How should I know?我怎么会知道?(意为:我不知道。) 6.must表示“偏要,硬要”。如: Must you make so much noise? 你非得弄出这么大声响吗? 7.may作“可以”讲时,其否定式常用“mustn't”表示“禁止”;must作“必须”讲时,其否定式是“needn't”,表示“不必”。如: —May I use your car? —No,you mustn't. ——我能用用你的车吗? ——不,一定不能。 (委婉的拒绝可用:Sorry,but I am using it now.或You'd better not.等) —Must I work out the problem tonight? —No,you needn't. ——我今晚必须做出这道题吗? ——不,不必。 8.need和dare的用法 need和dare两者既可用作情态动词也可用作实义动词。作实义动词时,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;作情态动词时,没有人称和数的变化(dare的过去式为dared), 直接接动词原形,多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。另外,dare作情态动词时,还可用于条件状语从句中,过去式为dared;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,大概”。如: He needn't do it.(情态动词) He doesn't need to do it.(实义动词) 他不必做这件事。 I didn't 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件事。 He didn't dare(to)do it.(实义动词) He dared not do it.(情态动词) 他不敢做这件事。注意:need作实义动词时,还可表示“需要”,后接动名词的主动形式表示被动含义(详见非谓语动词专题)。如: The floor needs sweeping. 这地需要打扫了。知识清单二　虚拟语气一、虚拟语气在非真实条件句中的运用