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1、情态动词,Modal verbs,citizen vest underwear otherwise transport per,n. 公民；居民 n. 背心；汗衫；坎肩 pron. 内衣 adv. 否则，不然 n. 交通运输系统;运输 prep. 每；每一,Words and Expressions,情态动词表示说话人的某种 感情或语气，对某一动作 或状态的某种态度。 表示“需要、可以、 必须、应当”等。,什么是情态动词？(modal verbs),Athletes at the ancient games could only be men who spoke Greek, but toda
2、y, men and women from around the world can compete.,We call the red words modal verbs.,Note 2,Note 1,Modal verbs,ability,certainty,permission,obligation,make requests,make suggestions,make offers,give advice,能力,义务, 职责,确定,许可,提出要求,给出建议,提供帮助,提出忠告,Words like can, will, may, must, and a few others are ca
3、lled modals. Modal verbs help other verbs express a meaning or an idea. Some common uses of the modals are these: Ability: He can speak English now. He couldnt speak English a year ago. Im not able to come to the game on Friday.,Obligation: You must fasten your seat belts. (strong) You should pay at
4、tention. (weak) You ought to pay attention. Certainty: It may rain. How could I forget an important thing like that? He cant /couldnt have known the result. Permission: All passengers may now board. We can board now.,Make requests: Can you help me with my training? Make suggestions: Shall we do some
5、 exercise this morning? Make offers: Ill wash your sports jacket. Shall I get a ticket for you? Give advice: You should not/ought not to eat a lot before swimming.,表示推测情态动词的重要用法,+ V. 常见 must be,+ V. / + be doing,+ have done,+ V.,must,may/might,+ V. / + be doing,+ have + done,可以用not表示“可能不”,cant/ coul
6、dnt,can/could,+ V. / + be doing,+V.,+ have done,+ V.,+ V. / + be doing,+ have done,在不表示推测的情态动词中, 我们要注意以下方面的问题:,1. 表示能力、许可的情态动词的用法。 2. shall 和 will 的多种意义的区别。 3. 表示否定的情态动词的用法。 4. 情态动词短语的使用。 5. 虚拟语气中情态动词的使用。,表示能力: can, could, be able to be able to 能用于各种时态。 can / could 只能表示现在或过去的能力。 was / were able to 设
7、法做成某事 相当于 managed to do sth. succeeded in doing sth.,1. 表示能力、许可的情态动词的用法。,表示许可: may / might, can / could might, could 比较委婉, 一般多用于疑 问句。 can, may 表达的语言比较随便。 在以could, might 表示征询对方意见 或表示请求时，回答应相应使用can, may。,2. 情态动词shall, will 的多种意义:,shall / will+ 动词原形:,* shall 可表示必须、命令、警告或征询意见。,* will 可表示意愿、常出现的动作，在疑问 句中
8、表示请求和建议。,* 均可表示将来。 过去时为 should, would。,3. 表示否定的情态动词的用法:,mustnt 不准; 禁止 neednt 没必要 ( = dont have to ) cant 不能; 不可能 may not 不可以; 可能不 shouldnt 不应该 ( = ought not to ),部分情态动词的否定式是情态动词中的考点之一。,不同的“肯定”程度可按下列层次排列： He is at home. (事实) He must be at home.（非常肯定的推断） He ought to be at home.（很可能） He could be at hom
9、e.（很可能） He may be at home.（仅仅可能而已） He might be at home.（或许, 非常不确定） He couldnt be at home.（很可能不在家） He cant be at home.（一定不在家） He isnt at home.（事实）,4. 情态动词短语的使用:,would like to do would rather do would rather + 从句 would prefer to do. had better do.,5. 用于虚拟语气的情态动词:,should might could would neednt ought
10、to,既可做情态动词又可做普通动词,情态动词 (+动词原形),行为动词,.,need,dare,1. 无人称和数的变化;,2. 尤其用于：,*否定句及疑问句中;,*在if/whether之后;,*或与hardly, never, no one, nobody连用;,3. 常以neednt 和darent 的形式出现;,4. dare有其过去时dared.,多用于肯定句; (sb.) need to do dare to do need to be done need doing,need / dare,注意对need问句的回答: -Need I finish the work today? -
11、Yes, _. No, _. No, _.,you must,you neednt,you dont have to,neednt 对其它情态动词的回答: -Shall I tell John about it? -No, you _. -Must we do it now? -No, you _.,neednt (dont have to),neednt (dont have to),dare可用实意动词和情态动词，用作情态动词时，意思是“敢”，其后接动词原形，通常只用于否定句或疑问句以及if或whether之后，一般不用于肯定句。如： Dare you tell her the truth
12、？ 你敢告诉她事实真相吗？ I dont know whether he dare try. 我不知他是否敢试一试。 I darent ask her for a rise. 我不敢要求她加薪。,dare用作实意动词时意为“敢于”，可以有各种词形变化，可用于各类句型（肯定句、否定句、疑问句及各类从句等），其后多接带 to 的不定式，有时 to 也可省去（尤其是在否定句或疑问句），可用于非谓语形式，完成时态等。如： We must dare to think, speak and act. 我们必须敢想、敢说、敢做。 I wonder how he dares (to) say such thi
13、ngs. 我纳闷他怎么竟敢说出这样的话来。,情态动词dare可以有过去式dared，但也可以直接用dare表示过去式，或后接动词完 成式。如： That was why he dared do so. 那就是他为什么敢这样做的原因。 Mother dare(d) not tell father shed given away his old jacket. 母亲不敢告诉父亲她把他的旧上衣送人了。,dare的过去式问题,dare后通常不接动词的进行式。,Nobody need to be afraid of catching the disease. Nobody need be afraid
14、of catching the disease.,These dishes need be cleaned carefully. These dishes need to be cleaned carefully. These dishes need cleaning carefully.,判断正误:,How dare you say such a thing? How dare you to say such a thing?,He darent to speak English before such a crowd, did he? He darent speak English bef
15、ore such a crowd, dare he?,情态动词的语法特征,1. 情态动词不能单独做谓语，除ought 和have外，后面只能接不带to的不定式。,2. 情态动词没有人称、数的变化，但有 些情态动词，如can, will也有一般式 和过去式的变化。,只作情态动词的 can/could, may/might, ought to, must 可情态可实义的 need, dare/dared 可情态可助动词的 shall/should, will/would 相当于情态动词的 have to, used to,3. 情态动词的“时态”形式并不是时间区别 的主要标志，不少情况下，情态动词
16、的 现在式形式和过去式形式都可用来表示 现在时间、过去时间和将来时间。,1. can的主要用法是： A. 表示体力或脑力的能力： eg. The girl can dance very well. B. 表示说话者的推测事物的可能性: eg. Can the news be true? C. 在口语中, can可以表示请求或允许： eg. Can I sit here?,can和could,2. could的主要用法是： A. could 是can的过去式, 表示与过去 有关的能力和推测: eg. We all knew that the young man couldnt be a doctor.
