高考英语专题复习讲义——情态动词和虚拟语气
展开情态动词和虚拟语气
情态动词
I.情态动词基本用法
情态动词 | 用 法 | 否定式 | 疑问式 | 简答式 |
can | 能力（体力，智力，技能） 允许或许可（口语中常用） 可能性（表猜测，用于否定句或疑问句中） | can not / cannot /can’t do | Can…do…? | Yes,…can. No,…can’t. |
could | couldn’t do | |||
may | 可以（问句中表示请求） 可能，或许（表推测） 祝愿（用于倒装句中） | may not do | May…do…?
| Yes,…may. No,…mustn’t/can’t. |
might | might not do | Might…do…? | Yes,…might No,…might not. | |
must | 必须，应该（表主观要求） 肯定，想必（肯定句中表推测） | must not/mustn’t do | Must…do…? to. | Yes,…must. No,…needn’t/don’t have |
have to | 只好，不得不（客观的必须，有时态和人称的变化） | don’t have to do | Do…have to do…? | Yes,…do. No,…don’t. |
ought to | 应当（表示义务责任，口语中多用should） | ought not to/oughtn’t to do | Ought…to do…? | Yes,…ought. No,…oughtn’t. |
shall | 用于一三人称征求对方意见 用于二三人称表示许诺、命令、警告、威胁等 | shall not/shan’t do | Shall…do…? | Yes,…shall. No,…shan’t. |
should | 应当，应该（表义务责任） 本该（含有责备意味） | should not/shouldn’t do | Should…do…? |
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will | 意愿，决心 请求，建议，用在问句中would比较委婉 | will not/won’t do | Will/Would…do…? | Yes,…will. No,…won’t. |
would | would not/wouldn’t do | |||
dare | 敢（常用于否定句和疑问句中） | dare not/daren’t do | Dare…do…? | Yes,…dare. No,…daren’t. |
need | 需要,必须（常用于否定句和疑问句中） | need not/needn’t do | Need…do…? | Yes,…must. No,…needn’t. |
used to | 过去常常（现在已不再） | used not/usedn’t/usen’t to do didn’t use to do | Used…to do…? Did…use to do…? | Yes,…used. No,…use(d)n’t. Yes,…did. No,…didn’t. |
II.情态动词的重点知识
表示“能力、许可”的can和may | 表示能力的情态动词用can/could | A computer_____think for itself; it must be told what to do. A.can’t B.mustn’t C. may not D.might not |
表示许可时用may/might ,can/could 都可以，但在问句中用could…?或might…？ 以使口气委婉客气，其回答一定要用can或may，以使回答口气明确（must表示一定，必须，mustn’t表示禁止，不许可）。 | ①—Could I call you by your first name? —Yes, you______ A.will B.could C.may D.might ②Johnny, you_____play with the knife, you_____hurt yourself. A.won’t/can’t B.mustn’t/may C.shouldn’t/must D.can’t/shouldn’t | |
在肯定句中could不可以用来表示过去某一特定场合的能力，而要用was/were able to。 | The fire spread through the hotel very quickly but everyone_____get out. A.had to B.would C.could D.was able to | |
表示“推断、判断”的can may,must | 在肯定句中都可以用来表示可能。在含义上must语气最肯定,may表示的是事实上的可能性。 | Peter______come with us tonight, but he isn’t very sure yet. A.must B.may C.can D.will 而can表示的是逻辑上的可能性： Mary is in poor health. She can be ill at any times. |
在否定句中只能用can和may。所以can’t时用以代替mustn’t，语气比may更肯定。中文可以翻译为不可能。 | Michael______be a policeman, for he’s much too short. A.needn’t B.can’t C.should D.may | |
在疑问句只能用can，不能用may和must。 | He may be very busy now. Can he be very busy now? He must be very busy now. Can he be very busy now? | |
need | need作为情态动词只有一种形式，只用于否定句和疑问句。 |
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dare | dare作为情态动词用时有两种形式：dare和dared两个词形，除了可以用于否定句和疑问句外，还可以用于条件从句或表示怀疑的句子中。 | If he dare come,I will kick him out. I don’t know whether he dare say. 注意:He doesn’t dare(to)answer the question.（否定句） Does she dare(to)enter the dark room?（疑问句） |
shall | 用于第一人称：征求对方的意见。 | What shall we do this evening? |
用于第二、三人称：警告、命令、允诺、威胁等。 | You shall fail if you don’t work harder. 警告 He shall have the book when I finish reading.允诺 He shall be punished.威胁 | |
should | 劝告、建议、命令、应该做、道义上的责任。 | You should(ought to) go to class right away. I should(ought to) help him because he is in trouble. |
will/would | 请求、建议，would比will委婉客气。 | Would you pass me the book? |
表示意志、愿望和决心。 | I will never do that again. They asked us if we would do that again | |
would可表示过去反复发生的动作或某种倾向。 | During the vacation he would visit me every week The wound would not heal.（伤口老是不能愈合） | |
would表示估计或猜想。 | It would be about ten when he left home. What would she be doing there? | |
情态动词+have done的用法 | could+have done：本可以做而实际上未能做。 | You could have done better, but you didn’t try your best. |
cannot+ have done：表示对现在或过去行为的否定推测。 | He cannot have been to that town. | |
can+主语+ have done：表示对过去行为的怀疑或不肯定（用在疑问句中）。 | Can he have got the book? | |
might(may)+ have done：对过去发生的行为不太肯定的推测。 | He may not have finished the work. If we had taken the other road, we might have arrived earlier. | |
must+ have done：对过去发生的行为肯定的推测。 其否定式为：cannot have done。 | You must have seen the film. You cannot have seen the film. | |
needn’t+ have done：本来不必要做的而实际上又做了。 | You needn’t have watered the flowers,for it is going to rain. 注意：didn’t need to(have to)do： 没有必要做而实际上也没有做 I didn’t need to clean the windows.My sister did it 2 hours ago. | |
should(ought to)+ have done：本来应该做而实际上又没有做。其否定形式表示某中行为不该发生却发生了。 | You should have started earlier, but you didn’t. She shouldn’t have taken away my measuring tape, for I worked to use it. 注意：He should have finished the work by now.（表推测） |
虚拟语气
类 别 | 用 法 | 例 句 | |
If引导的 条件从句 | 与现在事实相反 | 从句动词：过去式（be用were） 主句动词：should/would/could/might+do | If he were here, he would help us. |
与过去事实相反 | 从句动词：had+done 主句动词：should/would/could/might+have+done | If I had been free,I would have visited you. | |
与将来事实相反 | 从句动词：过去式/should+动词原形/were+to do 主句动词：should/would/could/might+动词原形 | If it should rain tomorrow, we would not go camping. | |
省略if的虚拟条件句 | 将虚拟条件从句中的were，had,should放到主语之前，构成主谓倒装 | ①Should he come ,tell him to ring me up. ②Were I you,I would not do it. ③Had I been free,I would have visited you. | |
混合虚拟条件句 | 不同时间的虚拟：各遵守各的规则 | ①If he had listened to me, he would not be in trouble now. ②If he had told me yesterday,I should know what to do now. ③If I were you, I would have gone to her birthday party. | |
虚拟与陈述的混合：各遵守各的规则 | ①He could have passed the exam,but he wasn’t careful enough. ②You should have come earlier.The bus left a moment ago. | ||
含蓄虚拟 条件句 | but for+名词表示虚拟条件 | 句子或主句中的谓语动词的形式视具体情况而定。这是考查考生应变能力的最佳试题。 | ---But for your timely warning,we ______ into great trouble. ---You know we’re friends. A. would get B. must have got C. would have got D. can’t have got |
without+名词表示虚拟条件 | Without the air to hold some of the sun's heat, the earth at night would be freezing cold. | ||
动词不定式表示虚拟条件 | It would be only partly right to follow in this way. | ||
现在分词表示虚拟条件 | Having known in time ,we might have prevented the accident.要是及时得知的话，我们也许能阻止这场事故。 | ||
过去分词表示虚拟条件 | Given more attention, the tree could have grown better. | ||
副词otherwise表示虚拟条件 | I was too busy at that time.Otherwise,I would have called you.我当时太忙，否则我就给你打电话了。 | ||
连词but连接的句子表示虚拟条件 | He _____fatter but he eats too little . A. would become B. would have become C. must become D. must have become | ||
其它 状语从句 | as if/as though引导的状语从句中动词用did或had＋done或would／could／might＋do。 注意：as if/as though引导的状语从句中也可以用陈述语气： 当说话者认为所述的是真实的或极有可能发生或存在的事实时： It sounds as if it is raining．听起来像是在下雨。 | ①与现在事实相反 He talks as if he knew where she was． ②与过去事实相反 He talks about Rome as if he had been there before. ③与将来事实相反 He opened his mouth as if he would say something. | |
in order that/so that引导的状语从句中动词用can/could/may/ might/ would等+do | Turn on the light so that we can see it clearly. | ||
宾语从句 | demand, suggest, order, insist后接的从句中动词为should+do | He suggested that we not change our mind. | |
wish后的从句中分别用过去式，过去完成式和should/would+do表示与现在，过去和将来情况相反 | I wish I could be a pop singer. I wish I would have gone to Shanghai last month. | ||
主语从句 | 在It is necessary / important / strange that… It is suggested / demanded/ ordered / requested that…等从句中， 谓语动词用should+do | It is strange that such a person should be our friends. | |
其它 句型中 | It is time that…句型中动词用过去式或should+do | It’s high time that we left/should leave. | |
would rather所接的从句中动词用过去式或者过去完成式 | I would rather you stayed at home now. | ||
If only句型中动词常用过去式或者过去完成式，表示强烈的愿望 | If only our dream had come true! | ||
