语法：be动词和情态动词
动词是表示动作或状态的词，按其词义和在句中的作用可分为行为动词、助动词、连系动词和情态动词。
语法：be动词
be动词作谓语时要与主语的人称和数保持一致。
be 动词与主语的人称一致
I am a new student.
You are a good boy.
He/She/It is in the sitting-room.
We/They are having an English class now.
be动词与主语的数一致
The car is new.
Our books are in the desk.
There is some milk in the bottle.(不可数名词作主语，be动词用单数)
be动词的否定形式：am not(没有缩写形式)，are not=aren’t, is not=isn’t.
be动词的过去式：am,is的过去式是was; are的过去式是were. 如：
Where is the camera? It isn’t there now. It was there a moment ago.
Su Hai and Su Yang were in the same class a year ago.
语法：情态动词
情态动词本身有一定的词义，但它必须和实义动词原型一起构成句子谓语。情态动词有：can, must, could, would, may, shall, should等。
其否定形式为：can not=can’t, must not=mustn’t,
could not=couldn’t, would not=wouldn’t,
may not(无缩写形式)，shall not(无缩写形式),
should not=shouldn’t. 如：
Can you speak English?
Would you like a cup of tea?
Shall we go to the park by bus?
You may go with us.
注意：在情态动词后应用动词原型。如：Can you fly a kite?
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