高中英语情态动词讲解

1、Grammar: Modal verbs,How many modal verbs do you know?,can could may might shall should must will would ought to,have to dare (darent) need (neednt) used to,表示推测,不表示推测,modal verbs,1. 情态动词有一定的意义，只表示期待或估计某事的发生，不能表示正在发生或已经发生的事情。 2. 没有人称和数的变化，即情态动词第三人称单数不加-s。 3. 不能独立使用，它和后面的动词构成谓语。 4. 情态动词除ought和have外，后

2、面只能接动词原形 5. 情态动词没有非谓语形式，即没有不定式，分词等形式。,只作情态动词的 can/could, may/might, ought to, must,可情态可实义的 need, dare,可情态可助动词的shall/should, will/would,相当于情态动词的have to,情态动词的语法特征,位置: 情态动词在句中放在谓语动词之前, 谓语动词前若有助动词,则在助动词之前,疑问句中, 情态动词则在主语之前。,I can see you. Come here. 我能看见你，过来吧。 He must have been away. 他一定走了。 What can I do

3、 for you? 我能帮你吗？ How dare you treat us like that！ 你怎能那样对待我们！,1. 表示能力或客观可能性，还可以表示请求和允许。如： Can you finish this work tonight? Man cannot live without air. Can I go now? Yes, you can.,can和could的用法,注意：could也可表示请求，语气委婉，主要用于疑问句，不可用于肯定句，答语应用can（即could不能用于现在时态的简略答语中）。如： Could I come to see you tomorrow? Yes,

4、 you can. （否定答语可用No, Im afraid not.） can表示能力时，还可用be able to代替。如： Ill not be able to come this afternoon.,2. 表示惊异、怀疑、不相信的态度。（主要用在否定句、疑问句或惊叹句中）,Can this be true? How can you be so careless! This cannot be done by him.,3. “can(could) + have + 过去分词”的疑问或否定形式表示对过去发生的行为怀疑或不肯定。如：,He cannot have been to that

5、 town. Can he have got the book?,4. cannottooenough表示无论怎样也不过分,越越好,eg. I cannot thank you too much for all your help to me. You cannot be too carefull when you traveling alone.,may和might的用法,1. 表示许可。 表示请求、允许时，might比may的语气更委婉一些，否定回答时(口语中常用) no , you cant . or , yes, please 用mustnt表示“不可以”、“禁止”、“阻止”之意(具有

6、强烈禁止的意思)如：,You may drive the car. Might I use your pen? No, you mustnt. 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。在日常口语中，用Can I . 征询对方意见在现代口语中更为常见。,2. 用于祈使句中表示祝愿。如： May you succeed! May you have a nice day!,3. 表示推测、可能（疑问句不能用于此意）。 He may be very busy now. 4. “may(might) + have + 过去分词”表示对过去发生的行为的推测。如： He may n

7、ot have finished the work.,will和would的用法,1. 表示请求、建议等，would比will委婉客气。如： Would you pass me the book? 2. 表示意志、愿望和决心。如： I will never do that again. They asked if we would do that again.,3. 用“will be”和“will(would) + have + 过去分词”的结构表示推测，主要用于第二、三人称。前者表示对目前情况的推测，后者表示对已经完成的动作或事态的推测。如：,This will be the book y

8、ou want. He will have arrived by now. The guests would have arrived by that time. I thought you would have finished this by now.,It would be about ten when he left home. What would she be doing there? I thought he would have told you all about it.,4. Would可表示过去反复发生的动作或某种倾向。Would表过去习惯时比used to正式，并没有“

9、现已无此习惯”的含义。如：,The wound would not heal. During the vacation he would visit me every week.,5. 表料想或猜想。如,Would更多的用来表示语气而不是时态 Will/would you please do., Would you like to do., Would you mind doing. 都表示建议、询问、请求等。 e.g., Would/ Will you mind opening the windows? I would / will do anything for you , sir. 有时

10、甚至只能用would而不用will e.g., I would like. Would you like.? They would love. He would rather ,2. “must be + 表语”的结构表示推测，它的否定或疑问式用can代替must。 This must be your pen.,3. “must + have + 过去分词”的结构常用在肯定句中，表示对过去发生的行为的推测。它的否定或疑问式用can代替must。 He must have been to Shanghai.,shall和should的用法,一.Shall的用法：,1. Shall用于第一、第三人

11、称疑问句中，表示说话人征求对方的意见或向对方请示。如：,Shall we begin our lesson? When shall he be able to leave the hospital? What shall we do this evening?,2. Shall用于第二、第三人称，表示说话人给对方命令、警告、允诺或威胁。如：,You shall fail if you dont work harder. He shall have the book when I finish reading. He shall be punished.,（警告）,（允诺）,（威胁）,二.Sho

12、uld的用法：,1. Should表示劝告、建议、命令，其同义词是ought to；在疑问句中，通常用should代替ought to。如：,You should go to class right away. Should I open the window?,Should的含义较多，用法较活，现介绍三种其特殊用法。请看下面的句子： I should think it would be better to try it again. 我倒是认为最好再试一试。 You are mistaken, I should say. 依我看，你是搞错了。 I should advise you not

13、to do that. 我倒是劝你别这样做。 This is something I should have liked to ask you. 这是我本来想问你的。,从以上例句可以看出：情态动词should用于第一人称时可以表示说话人的一种谦逊、客气、委婉的语气。,Should还可以用在if引导的条件从句，表示一件事听起来可能性很小，但也不是完全没有可能。相当于“万一”的意思。从句谓语由should加动词原形构成，主句谓语却不一定用虚拟语气。如：, Ask her to ring me up if you should see her. If you should change your mind, please let us know. Should I (If I should) be free tomorrow I will come.,你万一见到她，请让她给我打个电话。,万一你改变主意，请通知我们。,万一我明天有时间，我就来。,此外，Why(or How) + should结构表示说话人对某事不能理解，感到意外、惊异等意思。意为“竟会”。如：, Why should you be so late today? 你几天怎么来得这么晚？ Where is Betty living? 贝蒂住在哪里？ How should I