Be动词的形式： be, is, am, are, was, were, being, been
1.The man is back
2.They are back
3.He was back
4.They were back
5.They have been back
be动词的用法 后面接名词，形容词，地点副词，或短语做补足语
1.The man is a teacher
2.Mary's new dresses are colorful
3.My mother was in the kitchen
be动词的否定，在am, is, are, was, were 后面加 not, 缩略式am not, isn't, aren't, wasn't, weren't,
1.The man isn't back
2. I am not back
3. They aren't back
4. He wasn't back
5. They weren't back
使用be动词提问和回答
1. Is he a teacher?
Yes, he is (a teacher 省略回答) / No, he isn't
2. Are you a teacher?
Yes, i am / No, i am not
3.Were They Teachers?
Yes, they were / No, they weren't
