高中英语情态动词的用法

高中英语情态动词的用法一概述情态动词的共性1) 情态动词一般直接加动词原形, 除ought + to do sth .在否定句或疑问句中to 可以省略2) 情态动词不会因为主语的人称与数的变化而发生变化3) 当情态动词表达与说话同时或说话之后的情况,直接加动词原形(do sth/be done) .在简略回答时直接用情态动词(---Can you drive a car? ---- Yes, I can)(1)She said he might come to the farewell party (表达说话之后的情况)(2)She told me that he must be ill, for his face was pale(表达与说话同时情况)4) 当情态动词表达说话时已发生的情况,加动词完成式( have pp/have been pp)在简略回答时用情态动词+ have (---- Did he go to the cinema? ---- No, he should have, but he had to finish a report)(1) She may have been there yesterday(2) She should have come to his rescue when he was trapped in the elevator last night(3) He must have been praised at the meeting the other day二情态动词用法1 can1)表示现在或将来的能力,2)表示可能性“可能”(1)在肯定句中指逻辑推理的可能性，不指具体的事情的可能性，即泛指的可能性但在否定句或疑问句中可以表达具体一件事情的可能性 A: Driving carelessly can be dangerous B: Too much stress can drive a person mad C:Everybody can make mistakes in his life D: There being too much snow on a highway can lead to accidents(2) 在否定句中表示“不可能”A: He can?t be hungry B: She can?t have been criticized at last week?s meetingC: She can?t possibly be tired(3) 在疑问句中表示“可能吗,”A: Can she have been to the scenic spot last Friday? (4) S + can have (been)+pp表示“可能已发生某事”，一般用在否定句或疑问句，如: Can she have been to the scenic spot last Friday? (5)在肯定句中还可以表示“有时可能” A: Scotland can be very cold in winter B: He is a bad-tempered guy, but he can be quite charming when he wishes C: You can be very annoying 总之can表示可能性“可能”时可以用在肯定句、否定句和疑问句中。

3)表示“允许”，相当于may, can?t 表示“不可以,不能”(1) You can park here (2)He can?t take the magazine out of the library4)表示“可以”,在疑问句中主语常是第一人称或第三人称如:(1) Can I watch TV after I have finished my job? (2) Can he do me a favor by opening the door?2 could1) 表示过去的能力 (1)I could climb any tree when I was young (2) I got up early so that I could catchthe early bus2) 表示过去的可能性 (1)He could be very naughty when he was a boy(2) She said that he couldn?t be hungry(3)She told me that he couldn?t have left here3) 有时could可以代替can 表示现在或将来的情况(1) Could (=Can) you send me an application form?(表示“委婉提出请求”) (2) Could this be true? (表示“可能”) (3) ---- Who is the man? ---- He could/may/might/be our principal(表示“可能”)注意:在肯定句中一般不用can表示具体的某一件事情的可能性，但可以用could在肯定句中表示具体的某一件事情的可能性)4)can have pp与could have pp的区别A: can have pp一般只能表示可能已发生了某事，用在否定句或疑问句中，一般不用在肯定句中且不表达虚拟语气 B:could have pp 既可以表示可能已发生了某事，等于can have pp,也可以表达虚拟语气“本来能够做某事但实际未做”注1意:当主句的谓语动词是过去式时，那么从句在表示可能已发生了某事时，只能用could have pp 如: He said that shecouldn?t have committed suicide3 may1)表达“可以” 在疑问句中主语常用“I”(1) May I have your a ttention, please? (2) May I have your name? (3) You may watch TV after you have finished your homework(4)You may come if you wish (5) Dogs may not betaken into the houses2) 在肯定句表示“可能”，常指根据具体的已知的信息，表达具体的某一件事情的可能性。

如果表示说话同时或之后的情况用 may do sth;如果表示说话时已发生的情况用 may have (been) pp;如果表示说话时正在发生的情况用may be+doing;如果表示过去某一具体的时间正在发生的情况用 may have been doing 在否定句中表示“可能不”, 在表示“可能”时，一般不用在疑问句中(1)His face is pale; he may be ill (2) --- Who is the man speaking to our father?---- He may be our new headmaster (3) His room is dark; he may have gone out for adrive/walk/swim/rest (4) --- Where is the general manager? --- He may have seen the doctor, for he has caught a bad cold (5) He may have been watching TV at nine last night (6) She may be commenting on the newly released film now 3) may 在so that/in order that + 目的状语从句中表达“可以” 如:He works hard in order that he may be admitted to that famous college4) may 在让步状语从句中表达“可能”(1) No matter what you may have done, I have no interest(“may have done”从句谓语动词所表示的时间明显在主句所表示的时间之前)(2) Whoever you may be, he won?t let you in(“may be” 从句谓语动词所表示的时间与主句所表示的时间同时)(3)动词原型 + what + S + may, + 主句 A: Cost what the bookmay, I?ll take it(不管这书花多少钱,我都买) B: Come what may, I?ll take the side of you(不管发生什么事,我都支持你)5)may在祝愿语中的用法, May + 主语 + 动词原型!(1) May you succeed! (= Wish you success)(2) May all of you be happy!(= Wish all of you happiness!)6)may在常用句型中的用法,(1) S + may well do sth(很可能)如: She may well drop in for some tea on her wayto work (2) S + may/might as well do sth (不妨做某事,表示与说话同时或之后的情况)如:We may as well stay athome watching TV tonight (3) S + may /might as well have pp (不妨做某事,表示说话时已发生的情况)如:You mayas well have gone on an outing last week, but you just stayed at home doing nothing (4)I wish to do sth, may I?4 mightmay的过去式,一般表示过去的情况1) “可以”(1) I asked the acting manager if I might go home half an hour earlier today (2) He asked me if he might use the phone2) “可能,也许”(1) He said that he might be late with the supper(2)I guessed he might come tomorrow(注意:在以上的句中都不能用may代替might,因为当主句的动词是过去式时,从句中的情态动词也用过去式)(3) Hemight/may/could be our new English teacher(4) She might/may/could be watching the close football match(5) Tom might/may have finished the demanding task(6) ---- Can he have left his bag in the library?------ Yes, he might/may have(注意:这里的have不能省略)3)有时might代替may表示现在的情况, 语气更婉转或可能性更小(1) MightI use your phone? (2) Hemight/may/could tell his wife the news when he gets to the destination (3) He might/may/could be depending on you to give him a helping hand4) may have pp 与might have pp的区别 (1) may have pp 表示“可能”一般只用在肯定句“可能”或否定句中“可能不”而不表示虚拟语气(2) might have pp 既可以表示“可能”也可以表示虚拟语气“过去本来可以做但实际未做” 注意:主句的谓语是过去式时,从句中只能用might have pp表示“可能”5 must1) 表示必然性“一定”2(1) All of us must die2) 表示“必须,一定要,得”(1) You must cut down on smoking (2) I m ust remember to go to the bank today (3) I?m afraid I must be going3) 表示“义务”(1) Parents must send their children to school4)在肯定句中代替need表示“有必要” (1) --- Need I finish the exercises before I watch TV? ----- Yes, you must/No, you needn?t (2) You must get up early tomorrow morning5) mustn’t表示“不得,禁止,一定不要”(1) You mustn?t take photos here (2) We mustn?t be late for the meeting6) 表示“偏偏”(1) When I was busy cooking, the telephone must ring (2)When he was about to go to work, an unexpected visitor must come to see him (3) Why must you buy such an expensive dress when you are short of money?7)表示推测“一定”,只能用在肯定句中。