英语语法助动词PPT课件

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6)用作代动词，例如： — Do you like Beijing? — Yes, I do. （do用作代动词，代替like Beijing.） He knows how to drive a car,
doesn't he? 他知道如何开车，对吧？
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二、情态助动词
1 can/could
❖ (1)指主观能力。 Can指现在和将来。指过去的能力一般用was/were able to
Might用于间接引语；也表客观未实现的动作
He said he might order a taxi by telephone.
他说他可以用电话定出租车。
He might have fallen ill if he hadn’t take the medicine.
How long can you hold your breath under water？
That is easy.I can do that tomorrow.
could have done 用于虚拟语气指“过去本来能够却没有”
she should have explained the mystery.
English is becoming more and more important.
2)be + 过去分词，构成被动语态。如：
The window was broken by Tom.
English is taught throughout the world.
3)be + 动词不定式，可表示最近、未来的计划或安
Байду номын сангаас
years.
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助动词do 的用法: 1）构成一般疑问句。如： Do you want to pass the CET? 2）do + not 构成否定句。如： He doesn't like to study.
In the past, many students did not know the importance of English.
finished half of their work.
2）have + been +现在分词，构成完成进行时。如：
I have been studying English for ten years.
3）have + been +过去分词，构成完成式被动语态。 如：
English has been taught in China for many
助动词
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什么是助动词？
协助主要动词构成谓语动词词组的词叫助 动词（Auxiliary Verb）。被协助的动词称 作主要动词（Main Verb）。
助动词自身没有词义，不可单独使用。如：
He doesn't like English.他不喜欢英语。
（doesn't是助动词，无词义；like是主要 动词，有词义)
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分类及简介
❖ 助动词分为：基本助动词，情态助动 词，半助动词。
❖ 基本助动词：be，do，have
❖ 情态助动词：shall, will, should, would，could
❖ 半助动词：以be为中心成分，以have 为中心成分，以seem为中心成分。
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一、基本助动词
助动词be的用法： 1)be +现在分词，构成进行时态。如： They are having a meeting.
排。如：
He is to go to New York next week.
We are to teach the fre. sh persons.
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助动词have的用法:
1)have +过去分词，构成完成时态。如：
He has left for London.
By the end of last month, they had
What else can you say?（不耐烦）
How can I do such a thing ?(难办)
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❖注意
❖ Can与could 的区别与联系
❖ （1）Could是can的过去式，除具can的各种 功能外，还用来表示语气委婉。
❖ （2）Can和could还可以表示某人或某物一时 的特点指“有可能有时会”
她本可以解释这个秘密的。
❖ （2）表可能。Can 表可能时常用于疑问句和否定句，指某 事是否事实。
Can it be true?
We can’t change a law.
He said he couldn’t agree more.
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❖ (3)表允许用于非正式场合。
Can在肯定疑问句中表要求在否定句中表禁止。
It can be very misty in this area.
这里有时会大雾弥漫。
He could be very proud.
他有时会很骄傲
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2、may与might
（1）表示可以做或可能发生的事
He may come soon.
You may order a taxi by telephone.
Only when we begin our college life do we realize the importance of English.
只有在开始大学生活时我们才认识到英 语的重要性。
说明：引导此类倒装句的副词有never,
seldom, rarely, little, on. ly, so, well等。
3)构成否定祈使句。如： Don't be so absent-minded. 说明： 构成否定祈使句只用do，不用 did和does。
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4)放在动词原形前，加强该动词的语 气。如： Do come to my birthday party. I did go there. 5)用于倒装句，例如： Never did I hear of such a thing.
You can smoke in the entrance hall.
Can you lend me 2yuan?
Could 用于这个意义时只用于疑问句，语气更加委婉。
Could you please fetch us a few cups?
❖ (4)表感情色彩。表某种情绪。
What can satisfied her?(不满)