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.
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)
You can smoke in the entrance had 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)
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
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.
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。
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.
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。
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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.
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.
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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
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”
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
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.
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