免费学习英语情态动词与助动词

概念：

助动词本身无意思，在句中援助主要动词构成一定的时态，语态、语气，或是帮助构成否认句和疑难句，常用的助动词有be, do, have, shall(should), will(would).

情态动词表必定的词义，自身并不表示动作或状态，而仅仅表白说话人的态度，它在句中须跟主要动词一起形成谓语，重要的情态动词有can(could), may (might), must, have to, ought to, need, dare, shall, should, will, would.

1、免费学习英语can 能，可能，表说话人同意，英语，容许还可表客观条件许可，如:You can go now.

提倡导或要求时可用can I, can you表客气，如Can I buy you a drink?

can和be able to表才干时的差异。

can表个别存在的才能，be able to表在特定前提下的能力，如:Although the driver was badly hurt, he was able to explain what had happened.

2、may 

（1）、可以， ，表说话人同意，许可或请求对方允许。You may go.

（2）、（当初和将来）可能，兴许，只用于断定句和否定句中，如He may not be right.

3、免费学习英语must, have to

must表主观上的必需，have to表客观上的必须，免费学习英语例句如:It's getting late. I have to go. -Must I go now. -Yes, you must.

(No, you needn't./ No, you don't have to.) 

4、need, dare这二词有实意动词跟情态动词两种词性，如用作实意动词后接动词不定式to do，如用作情态动词后接动词原形。Need I go now? --Yes, you must./No, you needn't.) 

5、免费学习英语单词shall用于第一人称疑难句中表谈话人征求对方的见解或向对方请求，如，Shall we begin our lesson?

用于二、三人称陈述句，表谈话人命令、忠告、许诺、威胁等口吻，如: You shall fail if you don't work harder.

6、should表应该，意为有任务，有义务。如:We should try our best to make our country more beautiful.

7、will表有做某事的意志、意愿、安心、打算，如 "Will you lend me your book?" "Yes, I will."，

8、should have done表应当做而未做

     must have done表对从前事实的确定揣摩

     could have done表本能够做某事

9、判断句：肯定句用must, 否定句用can't, 不太肯定用may, 

He must be in the office now.

He must have gone to bed, for the light is out.

He can't be in the office. He is at home.

He couldn't have cleaned the classroom, because he didn't come here today.

He might be in the office, I am not sure.

He might have cleaned the room, I suppose.

II． 例题 内容来自

例1，They _______ to walk in the street at might. 

A. didn't dare B. not dared C. not dare D. dared not

解析，免费学习英语该题答案为A， 此空需选一动词作谓语，因为后面是to walk, didn't dare是举动动词dare从前时态的否定形式。

例2，When he was very old, Mr. Smith _______ sit for hours without saying a word. 

A. would B. should C. must D. used CopyRight .com

解析，该题谜底为A, would此处表过去的倾向性，习惯性动作，意为"总是"如: When we were children, we would go swimming every summer.

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