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1、有关情态动词的10条学习要点有关情态动词的10条学习要点 1. 弄清基本语法特点 情态动词就是表示说话的语气或情态的动词。常见的情态动词有can, may, must, need, dare, shall, will, should, ought to, have to, used to, had better, would rather等。情态动词具有以下3个特点： (1) 情态动词后面接动词原形并与动词原形一起构成谓语。 (2) 情态动词虽有时态的变化，但却没有人称和数的变化，即情态动词不会因为主语的人称或单复数的不同而用不同的形式。 (3) 变为疑问句或否定句时不需要助动词，而是将情态动
2、词移至主语前变为疑问句，直接在情态动词后加not，构成否定句。 2. 弄清表示能力的can / could和be able to的用法 (1) can表示具有某种能力或技能，意为“能，会”。如： Who can answer this question? 谁能回答这个问题？ (2)can 的过去式为could，但它通常只表示过去一般性能力，不表示过去特定场合下的能力，遇此情况要用 was were able to。如： Though the fire spread quickly through the hotel,everyone here was able to escape from b
3、eing killed. They were able to jump into the sea before the boat was blown up. 他们在船爆之前跳入海里。 3. 弄清表示许可的can / could / may / might / must的用法 can / could / may / might均可表示许可，只不过may较侧重讲话人的许可，而can较侧重客观情况的许可；could / might的语气比can / may更委婉、客气；在答语中表示允许别人做某事要can / may，不能用 could / might。如： Could Can, May, Might
4、 I use it? 我可以借用它吗? Yes, you can may. 可以。 must 表示必须作某事，其否定式mustnt表示“禁止，不准和告诫”。如： You mustnt cross in front of the traffic. 4. 弄清表推测的 can / may / could / might / should / must的用法 (1) 从所用句型来看：can用于否定句和疑问句，may用于肯定句和否定式，两者均可用于否定句，但是含义不同(can not不可能，may not也许不)；could, might 和 should 可用于肯定句、否定句和疑问句；must 表示
5、推测通常只用于肯定句。如： She cant be in the office now because I saw her on the street just now. She may not be free tonight. Can it snow with no dark clouds in the sky? (2) 情态动词：must,should,can,could,may,might均可表推测，但其果断性由强到弱，should 表示推测时，意为“想必，按理应该”，此外还有“居然，竟然，万一”之意，常指令人惊讶的事情。 如： “When can I come for the phot
6、os? I need them tomorrow afternoon.” “They _ be ready by 12:00.” A. can B. should C. might D. need 在四个选项中，首先可排除A和D，因为它们通常不用肯定句中；而B和C均可用于肯定句表示推测，但根据句意：顾客下午要照片，此时店主显然应用语气较肯定的should，而不宜用语气很不肯定的 might，否则顾客是不会满意的。 It is strange that she should be late. If it should rain tomorrow,dont expect me. What woul
7、d you do if the sky shouldwere to fall? 1 附：can在肯定句中表推测，只表理论或逻辑上的可能或当“有时”之意。而may表示事实上马上“应验”的可能性。 Mr Black is in poor health,and he can be ill at any time. Even experienced teachers can make mistakes. Be carefull,you may cut your finger. May亦可表祝愿，如 May you succeed in the future life！ May you have a s
8、afe journey！ 5. 弄清shall 与 will 的用法 (1) shall 除用于第一人称表示单纯将来外，还可用于陈述句第二、三人称,引导祈使句，或者与一，三人称搭配用于疑问句，同样引导祈使句。 No one shall be allowed to go out ahead of time during the exam. Who do you think is up to the task ? shall my students have a try? I have not got the reference book yet,but I will have a test on
9、 the subject next month. Do not worry.You shall have it by Friday. (2) will 可以表示“习惯,倾向性和特性”意为“ 老是总是就是”，will指现在，would指过去。另wil用在条件句中表意愿。 If you will not go,I will go instead of you. The cat will lie there all afternoon. Oil and water will not mix. Whenever I had some time,I would do some reading. Matc
10、hes will not strike if they are damp. 火柴潮湿就擦不。 Let us work together to make further progress,will you? (3) Shall I (we) she? 可用于征求意见等，Will you?可用于表示请求或邀请等。如： Shall I turn on the light? 要不要把灯打开? Will you join us for dinner? 你可否和我们一道去吃晚饭? 6. 弄清must表示“偏偏”的用法 情态动词 must 有时可以表示固执、偏激或碰巧，通常可译为“偏偏，偏要，硬要”,常指令
11、人不开心的事情，如： After I gave her my advice, she must go and do the opposite. 在我给她出主意之后她偏反着干。 The car must break down just when we were starting our holidays. 我们刚刚开始休假，汽车偏偏坏了。 If you must go,at least wait until the rain stops. The machine must break down at this busy hour. 7. need和dare的用法要点 need和dare可用作实义
12、动词和情态动词，用作实义动词时，后接动词要用不定式，有人称和数的变化，可用肯定句、否定句和疑问句；用作情态动词时，主要用于否定句和疑问句中，没有人称和数的变化，后接动词要用动词原形。如： We need to have lots of patience. 我们需要有很大的耐心。 He dared not go there at night. 晚上他不敢到那里去。He didnt dare( to) gothere at night. How dare you ask me such a question? how do you dare( to) ask me such a question?
13、 你怎么敢问我这样的问题? She didnt dare( to )meet her teachers eyes. How dare you go away when I am speaking to you? 2 注：need 表示“需要”，其后可接动名词，且要用主动形式表示被动意义。如： The room needs cleaningThe room needs to be cleaned. 这房间需要打扫了。 8. 弄清“情态动词+完成式”的用法(对已发事情的推测和判断) (1) must + have done：只用于肯定句，是对已发事情非常果断的推测和判断，意为“一定(已经)”。 I
14、t must have rained last night,for the ground is wet outside. (2) can + have done：用于否定句或疑问句，是对已发事情可能性的否定和质疑，意为“可能(已经)”。 I cant find my MP4 player.where can I have put it? He cant have finished the task quickly,which was given him a moment ago. (3) could + have done：意为“可能已经”“过去本能而事实上却没有”即可表推测亦可表对过去的虚拟
15、。 He could have visited the park yesterday since he is having a big talk about it today. If you had started earlier,you could have met your favorite star. (4) should ought to + have done：表示责备，遗憾等，意为“过去本来应该而事实上却没有”。 You should have finished the task ahead of time. I shouldnt have told her your secret
16、,but I didnt mean to hurt you. (5) needt + have done：用于否定句或疑问句，用于否定时意为“过去本来不必而事实上却”如： We needt have watered the vegetables since the storm is coming. (6) may + have done：用于肯定句或否定句，表示推测，意为“可能(已经)”。 You may not have really come to Chengdu ,the famous historical and cultural city. (7) might + have done
17、：用于肯定句或否定句，表示推测，意为“可能(已经)(此时 might 可换为 may)；另外还可以表示过去可能发生的事结果未发生，意为“本来会”(此时 might 不能换为 may)。 I cant find my MP4 player.I remembered I put it here just now. You might have put it in the wrong place. If we had taken the other way,we might have arrived earlier. would +have done:只表虚拟，意为“过去本欲而事实上却没有”， If
18、 he had won the game,he would have telephoned you earlier. I would have come to help you with the work ,but I was too busy. If you had spoken more clearly,you would have been understood earlier. (9)willshall+have done引导将来完成时， By the end of the century,we will have discovered other places in our sola
19、r system. 9. 弄清“情态动词+进行式”的用法 这类结构主要用于对一个正在进行的动作进行推测、责备、描述等。如： He might be waiting for you. 他可能在等你。 3 You should be wearing your sunglasses. 你应当戴着你的太阳镜。 He must be joking, or else hes mad. 他一定在说笑话，要不就是疯了。 Would rather的用法 后面直接接动原形，否定式在rather后加not。如： Hed rather work in the countryside. 她宁可到农村去工作。 Id ra
20、ther not tell you about it. 那件事我宁愿不告诉你。 Which would you rather have, tea or coffee?你喜欢喝茶; 还是咖啡? would rather. . . than. . . . 或would ratherthan表示“宁可不要或“与其不如”。如： Id rather play tennis than swim. (=Id play tennis rather than swim. ) 我宁愿去打网球而不愿去游泳。 注：当than后的动词原形与前面的动词原形相同时可以省去。如： Id rather go on Sunday
21、 than on Monday. 我宁愿星期天去而不在星期一去。 有时可将rather than置于句首来加强语气。如： Rather than refuse to help you, I would borrow money from my friends. 我宁可向朋友借钱，也不愿拒绝帮助你。 后接从句时，从句谓语动词要用过去式，表示与过去或现在的事实相反，从句如用过去完成时，表与过去的事实相反，如： Id rather you hadnt told him the news that day. 我真希望你那天没有把那消息告诉他。 Jim wants to see me tomorrow,
22、but I would rather he came today. would rather 接动词的完成式，表示“过去事与愿违的结果”。如： Id rather have left a note on her desk. 我本想留张字条在她书桌上的。 “At that time, I would rather have been a factory worker than an animal keeper,”he said. “那时，我宁愿做一个工厂工人，也不愿做动物饲养员，”他说道。 Did you scold her for her mistake yesterday? Yes,but I would rather not have done that. 4
