高考英语情态动词讲解

1、（一） 情态动词常考点（一） 表能力如：I am starving to death。Ican 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

2、个宾馆，但是每个人都能够逃出去。Icould have worked out the problem，but I didnt。（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

3、能性）Peter may come with us tonight，but he isnt 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wont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/migh

4、t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 cant/ couldnt 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。

5、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 didnt hear the phone。Imust 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

6、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。4. 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 timehe 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。（三） 表请求、允许、允诺1. 当对方是决策者时，你代表

7、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：Shall I（we）？Shall he/ she/ they？Would/ 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 tomor

8、row morning？Yes，you can/ may。（否定：No，Im 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：CouldI 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

9、 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）（四） 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dont have to do sth

10、. 或dont need to do sth. 或neednt do sth.；表示过去没必要做某事时，分为以下情况：当表示过去没必要做某事，但事实上却做了，用neednt have done sth.；当表示过去没必要做某事，而不涉及是否已经做了，可用didnt have to do sth. 或didnt need to do sth. 或It was not necessary to do sth.等。如：You neednt 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

11、体不好。Did you work very late last night？No，I didnt。Ididnt 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：Ishould go and visit him this afternoon，but I wonder if I will

12、 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）（五） “情态动词 + have done”用法一览表（六）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cant/ couldnt have doneIt must have rained last night，for the

13、road is quite muddy。The lights were off。They must have been asleep。can/ could have done“本来能够”“过去可能会”Can he have gone to his aunts？You could have come 5 minutes earlier。can/ could not have done“过去不可能”“过去没能”I saw Mr. Wang just now。He couldnt have gone to Beijng。may/ might have done“也许/或许已经”。一般只用于肯定句和否

14、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。Its 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。shouldnt/ ough

15、t not to have done“本不该做而做了某事”You shouldnt have told her the truth。neednt have done表示“做了本来不必去做的事”。注意：didnt need to do表示“没必要做并且实际上也没有做某事”。You neednt have taken a taxi here，for it was very near to my house。Ididnt 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

16、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 Iwould rather not hav

17、e done that。would like/ love to have done表示过去愿意做某事，但未做成。Iwould love to have gone to the party last night but I had to work extra hours to finish a report。（七） 情态动词其他用法要点1. cannot but + do sth.表示“不得不，只好”。如：Icannot 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

18、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

19、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 kn

20、ow？我怎么会知道？（意为：我不知道。）6. must表示“偏要、硬要”做某事。如：How old are you，madam？If you must know，Im twice my sons 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。7. may作“可以”讲时，其否定式常用“mustnt”表示“禁止”；must作“必须”讲时，其否定式是“neednt”，表示“不必”。如：MayI use your car？No，you mustnt。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Youd better no

21、t。等）Must I work out the problem tonight？No，you neednt。我今晚必须算出这道题吗？不，你不必。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

22、的to也可省略；I dare say是习惯说法，意为“我想，大概”。如：He neednt do that。（情态动词）他不必那么做。He doesnt need to do it。（行为动词）他不必做它。I didnt 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 didnt 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：T

23、he 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 cant have gone to school。I saw her just now

24、。（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 mustnt have met before。正：We cant 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

25、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 cant/ couldnt have gone to school。他肯定没去上学。2. 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：Youshoul

26、d/ ought to have come here earlier。You shouldnt/ ought not to have told her the news。Ishould have done my homework last night，but I watched TV instead。3. neednt + have done可用来表示“已做了不必做的事”。如：There is no school today。You neednt have come。4. could + have done可用来表示没做某事的遗憾。如：She came here on foot，but she

27、 could have come by bus。5. 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。6. 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，wasnt he？He must have been there，hasnt he？He must have been there yesterday，was he？He must have been there，has he？（二） 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 cant be telling us the truth。你不可能在对我们讲真话。Can he be still thinkin