商丘一高2015—2016学年度英语语法复习学案
情 态 动词
I 情态动词的特征： ① 本身有词义。 ② 不能独立作谓语。
3. 后接动词原形一起构成谓语。 4. 不随人称和数的变化。
II 情态动词各自的基本意义及用法： 一.can和could 情态动词 can /could 在肯定句中，表示客观可能性，并不涉及具体某事会发生，常用来说明人或事物的特征。要表达具体某事实际发生的可能性时，不用can，需用could，may，might。 表示请求和允许。表示请求，口语中常用could代替can，使语气更委婉。 1． Can we turn the air conditioner on? 2． Any police officer can insist on seeing a driver’s license. 3． In soccer, you can’t touch the ball with your hands. 4． Could you have her call me back when she gets home, please? 5． I wonder if I could just ask you to sign this. 表示能力 1．“I don’t think Mike can type.” “Yes, he can.” 2．I can speak fluent English now , but I couldn’t last year. 1． As a human being, anyone can make a mistake. 2． I’m confident that a solution can be found. 3． He can be very forgetful sometimes. 4． I may stay at home this weekend.（实际可能性） 5． Peter might come to join us.(实际可能性) 6． It will be sunny in the daytime ,but it could rain tonight.(实际可能性) 用法 例句 - 2 -
表示对现在的动作或状态进行主观的猜测，主要用在否定句和疑问句中。 表示惊异、怀疑、不相信等态度，主要用在否定句、疑问句和感叹句中。
特别说明：
1． It can’t be easy caring for a man and a child who are not your own. 2． Can the man over there be our head master? 1． Can this be an excuse for not giving them help? 2． This can’t be true. 3． How can you be so crazy? （1） could用来表示请求时，语气委婉，主要用于疑问句，不能用于肯定句，答语应用can
（即：could不能用于现在时态的简略答语中）。如： ——Could I use your dictionary?
——Yes, you can.(否定回答可用：No, I’m afraid not.) (2)
can和be able to辨析
can(could)和be able to都可以表示能力，意思上没有区别。但can只有现在式和过去式，而be able to则有更多的形式。如：
I’ve always wanted to be able to speak fluent English.
Those bags look really heavy, are you sure you’ll be able to carry them on your own? 但是，表示在过去某时的某一场合经过一番努力，终于做成了某事，通常不用could，而用was/were able to来表示。这时，was/were able to相当于managed to do或succeed in doing。如：
After the accident it was a long time before she was able to walk again. The fire was very big,but most people were able to escape from the building. (3) 惯用形式“cannot …too…”表示“无论怎么……也不（过分）”。如： You cannot be too careful.你越小心越好。
惯用形式“cannot but+ 不定式（不带to）”表示“不得不，只好”。如： I cannot but admire her determination.我不得不钦佩你的决心。 二．may和 might
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情态动词 may/ might 用法 例句 表示允许、许可。否定1． May I come in and wait? 回答一般用must 2． ——May I smoke here? not/mustn’t,表示“禁止、阻止”之意，但也可以用had better not (最好别)或may not（不可以），语气较为委婉。 在表示请求、允许时，1． Might I borrow your pen? might比may语气更委2． I wonder if I might speak to your son. 婉些。用May I征询对方许可在文体上比较正式，在口气上比较客气，在日常用语中，用Can I征询对方意见更为常见。 表示可能性的推测，通常用在肯定句和否定句中，含有“或许”“大概”“可能”之意；用might代替may时，则语气显得更加不肯定。 may用于祈使句表示祝愿 1． May you succeed. 2． Long may he live! 愿他能持续住下去。 3． May you have many more days as happy as this one. 4． May she rest in peace.愿她安息。 1． It may rain this afternoon. 2． She might come to join us this afternoon. 3． I suppose he might have missed the train. ——No, you mustn’t(或No, you’d better not.) - 2 -
惯用句式： “may well+ 动词原形”，意为“完全能，很1． It may well change forever the way you look at Greek art. 2． There may well be a real problem here. 3． There is nothing to do, so I may as well go to bed. 可能”，相当于to be 4． You may as well tell us now, we’ll find out sooner or later. very likely to “may as well或5． I suppose we might as well go home. 6． And if you have to plow the field anyway, you might as well plant it at the same time. might(just)as well+动词原形”意为“最好，满可以，倒不如”，相当于“had better或there is no reason to do anything else. 三．must和have to 情态动词 must 用法 表示“必须，应该”之意，语气比should，ought to强烈。其否定形式mustn’t表示“不准，不应该，禁止”等意 在回答带有must的问句时，否定回答常用needn’t或don’t have to，表示“不必”，而不用mustn’t 表示有把握的推测，意为“一定、准是、相必”，只用于肯定句中 1． It must be my mother. 2． You must be hungry after a walk. 3． There must be a hole in the wall. have to “必须，不得不”，意义与must相近。1． The film is not interesting. I really must 但must表示的是说话人的主观看法，而have to则往往强调客观需要。 go now. 2． I have to go now, because my mother is in hospital. 例句 1． You must come to school on time. 2． Everybody must obey the law. 3． You mustn’t drive so fast in the street. 4． We mustn’t waste any more time. 1．—Must I come back before ten? —Yes，you must.(No, you needn’t) - 2 -
must只有一种形式，即现在式与过去式都是一种形式，而have to则涉及各种人称、时态等方面的变化形式。 1．I had to work hard when I was your age. 2．I will have to learn how to use a computer. 3．In order to take the exam, we’ll have to finish the whole book by the end of this month . 两者的否定意义不同，mustn’t表示“禁止，不许”，don’t have to表示不必。 四．shall和should 情态动词 Shall 用法 用于第一、二、三人称构成的疑问句，表示征求对方意见或请求指示 例句 1． You mustn’t go there. 2． You don’t have to go there. 1． Shall I open the window? 2． Shall we say 6 o’clock, then? 3． What shall I get for dinner? 4. Don’t worry, you shall get the answer this afternoon.(允诺) 用于第二、三人称陈述句中，1． He shall be sorry for it one day, I tell you. （警表示说话人给对方的命令、警告、允诺或威胁。 告） 2． You shall do as I say. (命令) 3． If your children don’t do as I tell you, you shall not go to the party. (威胁) should 表示推测，用在肯定句中，对现在的情况或可能发生的事的主观推测或期待,意为“想必，大概，或许” 还可以用在if引导的条件句中，表示一件事听起来可能性1． Ask Tom to ring me up if you should see him. (你万一见到汤姆，请让他给我打个电话) 表示劝告或建议，意为“应该” 1． What should I do? 2． Should I trust him? 3． You should read his new book. 1． It should be a nice day tomorrow. 2． Try phoning Robert, he should be home now. 3． He should be around sixty years old. - 2 -
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