一、be 动词做系动词

1、系动词+表语”的结构

当be 动词做系动词使用时，主要构成“系动词+表语”的结构，在句子中做谓语。表语可以是名词、形容词、副词、介词短语等。例如：

The man is a science teacher.

Mary's new dresses are colourful.

Mother is in the kitchen now.

I have been there before.

They shall be here at 10:00 tommorow.

That can't be true.

You are not being very polite.

Your brother is being very annoying this evening

2、be 动词的一般疑问句，方法是把be 移到主语前面，也可说成是移到句首。

Is the man a science teacher? Yes, he is. / No, he isn't.

Are Mary's new dresses colourful? Yes, they are. / No, they aren't.

Was mother in the kitchen then? Yes, she was. / No, she wasn't.

Were you at home the day before yesterday? Yes, I was. / No, I wasn't.

Was she late this morning? Yes, she was. / No, she wasn't.

3、be 动词用在特殊疑问句

在特殊疑问句里，be 动词仍然移到主语前面，但特殊疑问句是以特殊疑问词开头的，所以be 动词只能说是移到主语前面，或者说是在特殊疑问词的后面。例如：

Whose bike is broken? Xiao Ming's bike is.

Who was singing in the room? Mr. Zhang was.

Where are you from? I am from Wuhu.

What class were you in? We were in Class 2.

How old is Tom? He is ten.

4、be 动词的否定句

be 动词做谓语时，它的否定形式是在be 后加not，并且可以缩写。例如：

It is not sunny today.

Tom and his friends are not in the park.

You were not nine years old when I went to the university.

He was not often late for his class when he was a student.

I wasn't here yesterday.

My parents weren't at home last Sunday.