文档介绍：动词的构成
be 动词
助动词
情态动词
系动词
实义动词
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be 动词
be动词的几种形式
am is are
was were
being
been
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be动词的用法
与名词、数词、形容词、介词连用
I am a doctor.
He is ten.
They are tired.
The cat is under the table.
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be动词的用法
There be 句型
用于不可数名词和可数名词单数之前
There is a pen on the desk.
There is some water in the glass.
用于复数名词之前
There are some sheep in the hill.
用于一般将来时
There is going to be a film in our school next Sunday.
用于一般过去时
There was a book on the desk yesterday.
There used to be (过去常)a tall tree here.
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be动词的用法
Be 动词在时态中的运用
在现在进行时中
We are talking （交谈）now.
在过去进行时中
We were talking （交谈） at this time yesterday.
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助动词
助动词的几种形式
do /don’t
does/ doesn’t
did/ didn’t
will /won’t
have, haven’t /has, hasn’t/had hadn’t
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助动词的用法
对句子进行否定和疑问
Do you get up early every day?
I didn’t （没）have lunch yesterday.
Will you be back soon?
He hasn’t （没）finished the work yet.
在反意疑问句中
He works in a school, doesn’t he?
She has never been there,has she?
在倒装句中
They helped the farmers , so did we.
I won’t visit the famous singer,neither will he.
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情态动词
共同特点
情态动词后面跟动词原型
无论否定、疑问、倒装句、或反意疑问句都用情态动词
只有时态变化，没有人称变化
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情态动词
解释
can / could
在表示请求允许的时候两者和互换， could比can语气更委婉。
Can I help you?
Could you open the window?
在表示有能力作某事时，could是can的过去式。
I can swim.
I could swim at the age of five.
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情态动词
Must /have to
Must 表示主观意愿，否定句用Mustn’t，否定回答用needn’t
I must go now.
You mustn’t play in the street.
Must I clean the room now?
No,you needn’t.
have to表示客观条件的限制的“不得不”，它有时态和人称变化，需要助动词来否定和疑问。
I don’t have to carry the big box.
He had to wash his clothes.
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