|
情态动词 主要用法 典句示例 have to 表示“必须；不得不” It’s getting dark.We have to go home now. shall 用于第一、三人称的疑问句中，表示征求对方的意见和向对方请示 Shall we put off the sports meeting until next week？ 用于第二、三人称的陈述句，表示说话人给对方的命令、警告、允诺或威胁；此外，当颁布法律、规定时也用shall You shall get an answer from me by tomorrow. It has been announced that candidates shall remain in their seats until all the papers have been collected. 情态动词 主要用法 典句示例 should 表示劝告和建议，作“应该，应当”讲 He should learn to be more polite. 表示推测，意为“按理说，应该，应该会” It should be a good movie—its reviews were very good. 用在if条件句中，表示可能性很小，但也不是完全不可能 If anyone should phone，tell him I’m in conference. (与疑问词连用，表示意外，纳闷，惊讶等)到底……，究竟是…… (用于表示感情，意志等句中的that从句)竟然……，居然…… Why should I help him？He’s never done anything for me. I’m surprised that you should speak in such a way. I’m glad that your story should have won the first prize. 情态动词 主要用法 典句示例 will/ would 用于表示意志或意愿 He will give his girlfriend anything she wants. 表示请求，建议。用would比will委婉、客气些 Would you like to come to my party？ 表示习惯：will可表示主语现在的习惯，常译为“总是，习惯于”。表示过去的习惯性动作时用would She will sit for hours reading in the afternoon. When he was young，he would listen to music alone in his room. 表示预料或猜想 That will be the postman ringing. 表示事物的某种性质或倾向 Wood will float on the water. 情态动词 主要用法 典句示例 need 表示需要；必要。用于否定句、疑问句和条件从句中 —Need we make the test？ —No，we needn’t. dare 意为“敢；敢于”，主要用于疑问句、否定句和条件从句中，一般不用于肯定句。I dare say是习惯说法，意为“我想，大概” How dare you talk like that？ ought to 表示义务、忠告等，意为“应当，应该” The dish is delicious.You ought to try some. 表示推测、可能性，意为“应该” He ought to be feeling better by this evening. 特别提醒： 1.表示经过努力而成功地做成某件具体事情时，一般用was/were able to，不用could。 The fire spread through the hotel very quickly but everyone was able to get out. 尽管大火迅速蔓延到了整个宾馆，但是每个人都逃了出去。 2.can的一些常用固定搭配： cannot but do sth./cannot help but do sth./cannot choose but do sth.表示“不得不，只好”。 cannot/can never...enough/too再……也不为过，越……越……。 3.may的一些常用固定搭配： may well＋动词原形意为“完全能，很可能”，may/might as well＋动词原形意为“最好，满可以，倒不如”。 4.must开头的问句，其否定回答用needn’t或don’t have to代替。 5.mustn’t表示“禁止、不许做某事”。 二、表示推测的情态动词用法比较一览表 情态动词 适用句式 适用时态 意义 典句示例 must 肯定句 一般时、进行时、完成时 一定、肯定 You must be hungry after the long walk. He must be sleeping in the dormitory. can(could) 疑问句，否定句 一般时、进行时、完成时 可能，能够 She can’t be reading in the reading room now. Can/Could this be an excuse for that？ 情态动词 适用句式 适用时态 意义 典句示例 may (might) 肯定句，否定句 一般时、进行时、完成时 也许，可能 He may not be happy. He may be playing basketball on the playground. should(ought to) 肯定句 一般时 待，“应该” He should be around sixty years old.(确定) It’s nearly seven o’clock，Jack should be here at the moment.(期待) will(would) 肯定句、否定句、疑问句 一般时、进行时、完成时 大概 He will have forgotten me.I left him 18 years ago. It would be about ten when he left home. 三、“情态动词＋have done”用法 类型 构成 主要用法 句式 典句示例 对过去 的推测 must have done 表示对过去已经发生的行为进行推测，意为“想必/准是/一定做了某事” 肯定句 You must have gone to bed late last night.Your eyes are red. can/could have done 表示对过去发生的行为的怀疑和不肯定 否定句、疑问句 He cannot have forgotten it. may/might have done 表示对过去已发生的行为的推测，意为“也许/或许/已经(没有)……” 肯定句、否定句 It’s too late.I think he may have gone to bed. 类型 构成 主要用法 句式 典句示例 表示后 悔、责备 或遗憾 could have done 表示虚拟意味，意为“本来能够(可以)……”(但实际并没有做) 肯定句 The accident could have been avoided. might have done 表示本来应该或可以做某事，含有轻微的责备语气 肯定句 You might have given him more help，though you were busy. should/ought to have done 表示本该做某事而实际上未做，否定形式表示做了本不应该做的事 肯定句、否定句 You are late.You ought to have arrived five minutes earlier. You shouldn’t have told her the news. 类型 构成 主要用法 句式 典句示例 表示后 悔、责备 或遗憾 needn’t have done 表示做了本来不必做的事 否定句 I actually needn’t have bought so much wine—only three people came. had better have done 用于事后的建议，含轻微责备的口吻，意为“当时最好做了某事” 肯定句、否定句 You had better have started earlier. You had better not have scolded her. would rather have done 表示“宁愿当时做了某事”(但事实上过去并未做) 肯定句、否定句 I would rather have taken his advice. I would rather not have said that. would have done“本愿意做而没做” would like/love to have done sth.过去愿意做但未做成 I would have gone to see the film with you but one of my friends came. I would love to have gone to the party last night，but I had to work extra hours to finish a report. 特别提醒： didn’t need to do表示过去不必做，也没做某事 He was only 5 years old and didn’t need to go to school. | 
