be动词的人称变化规则

be动词的几种形式和基本用法 am 当主语是第一人称单数(I)时用；is 当主语是第三人称单数(he, she , it )时用 ；are 当主语是you ,we和所有复数时用 was 在过去时中,当主语是第一人称单数,第三人称单数时替换am 和is；were 在过去时中,当主语是we ,you和所有复数时用,即替换are。

be动词的两种句子形式

(一) 肯定形式 主语+be+其它.

I am (I’m) a doctor.

2. You are (You’re) a doctor.

3. He is (He’s ) a doctor.

4. She is (She’s ) a doctor.

5. It is (It’s ) a cat.

6. This is a desk.

7. That is a desk .

8. We are (We’re ) doctors.

9. You are (You’re ) doctors.

10. They are (They’re )doctors.

11. These are desks. 12. Those are desks.

(二)否定句形式 主语+ be + not+其它 (构成方法 肯定句变否定句,只要在be 后+not 即可) 以上面的句子为例,将肯定句变为否定句.

I am not a doctor. (注 am 和is 不能缩写 )

2. You are not (aren’t ) a doctor.

3. He is not (isn’t ) a doctor.

4. She is not (isn’t ) a doctor.

5. It is not ( isn’t ) a cat.

6. This is not (isn’t ) a desk.

7. That is not (isn’t ) a desk .

8. We are not (aren’t ) doctors.

9. You are not (aren’t ) doctors.

10. They are not (aren’t ) doctors.

11. These are not (aren’t ) desks.

12. Those are not (aren’t ) desks.