高考英语情态动词讲解 6页

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  • 2021-05-13 发布

高考英语情态动词讲解

  • 6页
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(一) 情态动词常考点 (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)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的做了某事)尽管这场大火迅速蔓延到了整个宾馆,但是每个人都能够逃出去。‎ ‎ I could have worked out the problem,but I didn’t。‎ ‎(过去有能力做但未做)我本来可以解决这个问题,但没有解决。‎ (二) 表推测(可能性)‎ 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:‎ Accident can happen on such rainy days。‎ 这样的多雨天气有可能会发生事故。(客观的可能性)‎ Peter may come with us tonight,but he isn’t sure yet。‎ 彼得今晚可能和我们来,但他还没确定。(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 词形 肯定式 否定式 疑问式 must 必定,必然 ‎/‎ ‎/‎ will 很可能,大概 不会,不该 会……吗?‎ would 可能性比will小 语气比won’t弱 语气比will弱 should 说话者有较大的试探性 ‎/‎ ‎/‎ ought to 说话者有较大的试探性(含义同should)‎ ‎/‎ ‎/‎ can ‎/‎ 不可能 有可能吗?‎ could 可疑的可能 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。(表不相信)‎ 这不可能是他做的。‎ This may not be done by him。(表不确定)‎ 这可能不是他做的。‎ He could be on his way home now。(could不如may/ might常用)‎ 他现在可能在回家的路上。‎ Can this be done by him?(表示疑惑、惊讶)‎ 这可能是他做的吗?‎ Mr. Bush is on time for everything。How can it be that he was late for the opening ceremony?(表示疑惑、惊讶)‎ 布什先生做每件事都很按时。他怎么可能在开幕仪式上迟到呢?‎ I didn’t hear the phone。I must have been asleep。(表肯定)‎ 我没听到电话。我肯定已经睡着了。‎ 3. would,could,might并不一定与过去时间有关,而是表示可能性弱于他们相应的现在时形式。另外should也不一定与过去时间有关。如:‎ This may/ might be done by him。(后者比前者语气弱)‎ 这件事有可能是他干的。‎ 1. should/ ought to表推测时,表示说话者有较大的试探性。如:‎ He ought to/ should be here on time—he started early enough。‎ 他应该按时到这里——他出发的够早的。‎ We should arrive before dark。‎ 我们按说能在天黑前到达。‎ The roads should be less crowded today。‎ 今天路上应该不至于那么拥挤了。‎ (一) 表请求、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 I(we)…?②Shall he/ she/ they…?③Would/ Will you…?如:‎ Shall we begin our class?‎ Shall the driver wait outside?‎ When shall my father be able to leave hospital?‎ Would you do me a favor?‎ 2. could/ might/ would/ should表委婉语气的功能。如:‎ ‎—Could/ Might I use your bike tomorrow morning?‎ ‎—Yes,you can/ may。(否定:No,I’m afraid not。)‎ 不可以说,Yes,you could/ might。回答允许时,用could/ might表委婉是不恰当的。如:‎ ‎—Could I borrow your dictionary?‎ ‎—Yes,of course you can。‎ 3. 当你自己(I)是决策者,给对方(you)或第三者(he,she,they)以命令、警告、允诺或威胁时,要用shall。此外,当宣布法律、规定时,也要用shall。如:‎ You shall leave the room at once,and he also shall。(= I order you and him to leave the room at once。)‎ 你马上给我滚出去!他也一样。(说话者的意志)‎ It has been announced that candidates shall remain in their seats until all the papers have been collected。‎ 通知称在所有试卷收上来之前,应试者必须留在座位那里。(规则或规定)‎ (二) 表必要性 1. must常用来表示必要性,意为“必须”。表示现在或将来必须做某事用“must + 动词原形”;表示现在或将来不必做某事时,用don’t have to do sth. 或don’t need to do sth. 或needn’t do sth.;表示过去没必要做某事时,分为以下情况:①当表示过去没必要做某事,但事实上却做了,用needn’t have done sth.;②当表示过去没必要做某事,而不涉及是否已经做了,可用didn’t have to do sth. 或didn’t need to do sth. 或It was not necessary to do sth.等。如:‎ You needn’t have worded that late last night。It was harmful to your health。‎ 你昨晚本不必工作到那么晚,那对你的身体不好。‎ ‎—Did you work very late last night?‎ ‎—No,I didn’t。I didn’t need to work very late。‎ ‎——您昨天晚上工作到很晚了吗?‎ ‎——不是很晚,我没必要工作到很晚。‎ 2. should也可以表示必要性,意为“(义务上)应该”。should表必要性时,在语气上比must(必须)弱。“should + 动词原形”表示现在或将来应该做某事(的必要性);“should + have + 过去分词”表示过去本该做某事(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?‎ 你昨天应该参加那个会议。你缺席的原因的是什么?(表示过去的必要性)‎ (三) ‎“情态动词 + have done”用法一览表 (四) 情态动词 + 完成式 意义 例句 must have done ‎“想必/准是/一定做了某事”,否定式为can’t/ couldn’t have done It must have rained last night,for the road is quite muddy。‎ The lights were off。They must have been asleep。‎ can/ could have done ‎①“本来能够……”‎ ‎②“过去可能会……”‎ Can he have gone to his aunt’s?‎ You could have come 5 minutes earlier。‎ can/ could not have ‎①“过去不可能……”‎ I saw Mr. Wang just now。He ‎ ‎ done ‎②“过去没能……”‎ couldn’t have gone to Beijng。‎ may/ might have done ‎“也许/或许已经……”。一般只用于肯定句和否定句中(在否定句中表示“可能不”),不用于疑问句。用might则表示语气更加不肯定。‎ It’s too late。I think he may have gone to bed。‎ He may not have finished the work。‎ She might have caught a cold。‎ should/ ought to have done ‎“本该做某事,而实际上未做”‎ You should have come to the meeting earlier。‎ You ought to have done this exercise more carefully。‎ shouldn’t/ ought not to have done ‎“本不该做而做了某事”‎ You shouldn’t have told her the truth。‎ needn’t have done 表示“做了本来不必去做的事”。注意:didn’t need to do表示“没必要做并且实际上也没有做某事”。‎ You needn’t have taken a taxi here,for it was very near to my house。‎ I didn’t need to clean the windows。My brother did it。‎ had better have done 用于事后的建议,含轻微责备的口吻,意为“要是当时做了某事就好了”,其否定式had better not have done表达相反的含义。‎ You had better have started earlier。‎ You had better not have scolded her。‎ would rather have done 表示“宁愿当时做某事”,其否定式would rather not have done表达相反的含义,两者都表示“后悔”之意。‎ I would rather have taken his advice。‎ I raised objections at the meeting,but now I would rather not have done that。‎ would like/ love to have done 表示过去愿意做某事,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 report。‎ (一) 情态动词其他用法要点 1. cannot but + do sth.表示“不得不,只好”。如:‎ I cannot but choose to go。‎ 我只好去。‎ 2. may well和may as well结构 ‎(1)“may well + 动词原形”是一种常用结构,意为“完全能,很可能”,相当于to be very likely to。如:‎ He may well be proud of his son。‎ 他大可为儿子感到自豪。‎ 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。‎ ‎(2)“may/ might as well + 动词原形”意为“最好,满可以,倒不如”,相当于had better或to have no strong reason not to。如:‎ You may as well do it at once。‎ 你最好马上就做这件事。‎ You may as well stay where we are。‎ 我们留在现在的地方倒也不错。‎ 3. can not(或never)等否定词与enough连用表示“再……也不为过”。具体用法见形容词、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、惊异等,意为“竟会”。如:‎ Why should you be so late today?‎ 你今天来的怎么这么晚?‎ How should I know?‎ 我怎么会知道?(意为:我不知道。)‎ 1. must表示“偏要、硬要”做某事。如:‎ ‎—How old are you,madam?‎ ‎—If you must know,I’m twice my son’s age。‎ ‎——夫人,您多大了?‎ ‎——如果你硬要知道的话,我是我儿子年龄的两倍。‎ 2. 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。‎ ‎——我可以使用你的车吗?‎ ‎——不,不行。‎ ‎(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。‎ ‎——我今晚必须算出这道题吗?‎ ‎——不,你不必。‎ 3. need和dare的用法 need和dare两者既可用作情态动词也可用作行为动词。作行为动词时,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可以有过去式dared),直接跟动词原形,只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,还可用于条件句中,过去式为dared;作行为动词时,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 that。‎ ‎(情态动词)他不必那么做。‎ He doesn’t need to do it。‎ ‎(行为动词)他不必做它。‎ 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个。‎ He didn’t dare(to)do that。‎ ‎(行为动词)他不敢那么做。‎ He dared not do it。‎ ‎(情态动词)他不敢做它。‎ 注意:need作行为动词时,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。‎ 易错知识总结 (一) 易混点归纳 (一) ‎“情态动词 + have done”结构的用法区别 ‎“情态动词 + have done”这一考点,主要涉及以下几个结构:‎ 1. can(could)/ may(might)/ must + have done多用来对过去发生的情况作出语气强弱不同的推测。具体使用时请注意以下几点:‎ (1) can表推测,一般用于疑问句和否定句,极少用于肯定句。如:‎ ‎—Can she have gone to school?‎ ‎—No,she can’t have gone to school。I saw her just now。‎ (2) may表推测,一般不用于疑问句;疑问句中该用can,could或might。如:‎ How could he have forgotten such an important thing?(不用may)‎ Might you have met him somewhere?(不用may)‎ (3) must表推测,一般不用于否定句;否定句中应用can或could。如:‎ 误:We mustn’t have met before。‎ 正:We can’t have met before。‎ (4) 表推测时could,may,might用于肯定句语气较弱;must用于肯定句语气很强;may,might用于否定句语气较弱;can,could用于否定句语气很强。如:‎ He could/ may/ might have gone to school。‎ 他可能上学去了。‎ He must have gone to school。‎ 他肯定是上学去了。‎ He may/ might not have gone to school。‎ 他也许没去上学。‎ He can’t/ couldn’t have gone to school。‎ 他肯定没去上学。‎ 1. should/ ought to + have done在肯定句中表示“该做的事情没有做”,在否定句中表示“已做了不该做的事”。通常用来表示一种义务、自责或提出委婉的批评。如:‎ You should/ ought to have come here earlier。‎ You shouldn’t/ ought not to have told her the news。‎ I should have done my homework last night,but I watched TV instead。‎ 2. needn’t + have done可用来表示“已做了不必做的事”。如:‎ There is no school today。You needn’t have come。‎ 3. could + have done可用来表示没做某事的遗憾。如:‎ She came here on foot,but she could have come by bus。‎ 4. could/ might + have done也可用来表示委婉的批评。如:‎ You could have come 5 minutes earlier。‎ You might at least have written me a letter。‎ 5. 在反义疑问句中,表推测的情态动词不出现在简短问句部分。句中有过去时间状语的,问句部分用过去时,否则,用现在完成时。如:‎ He must have been there yesterday,wasn’t he?‎ He must have been there,hasn’t he?‎ He must have been there yesterday,was he?‎ He must have been there,has he?‎ (一) 情态动词后面接进行时的情况 1. can后面接进行时表示可能正在发生的动作。如:‎ What can she be doing at this moment?‎ 这个时候她会在做什么呢?‎ You can’t be telling us the truth。‎ 你不可能在对我们讲真话。‎ Can he be still thinking of what I told him?‎ 他会不会还在考虑我告诉他的那件事呢?‎ 2. may后面接进行时表示可能正在发生的动作。如:‎ Your mother may be waiting for you to return home。‎ 你妈妈可能正等着你回家呢。‎ She may be leaving for New York tomorrow or some day。‎ 她或许明天或者什么时候会动身去纽约。‎ They may be returning before Christmas。‎ 他们可能圣诞节前回来。‎ 3. might后面接进行时表示可能正在发生的动作。如:‎ They might be planning to make a loan for their new project。‎ 他们也许在为他们的新项目计划贷款的事。‎ She might still be crying for being wronged。‎ 她或许因为受了冤枉还在哭。‎ You might be telling me a lie。‎ 你也许在对我撒谎。‎ 4. must后面接进行时表示想必正在做某事。如:‎ You must be thinking where I learned it。‎ 你一定在想我是从哪儿知道这件事的。‎ They must be following us just a little behind us。‎ 他们肯定在离我们不远的地方尾随着我们。‎ My brother must be sleeping in bed for it’s so quite in the house。‎ 家里这么安静,我弟弟一定在床上睡觉。‎ 5. should后面接进行时表示应该正在做某事。如:‎ You should be doing your exercises instead of watching TV。‎ 现在你应该在做作业而不是看电视。‎ You shouldn’t be thinking about the solution only in one way。‎ 你不应该只用一种方法考虑解决问题。‎ Why should I be waiting here without doing anything?‎ 我凭什么在这儿白等?‎