Be动词的否定

在 am, is, are, was, were后面加not。
缩略：am not, isn't, aren't wasn't, weren't

• The man isn't back
• I am not back.
• They aren't back.
• He wasn't back.
• They weren't back.

使用Be动词提问和回答

• Is he a teacher?
  Yes, he is. / No, he isn't.
• Are you a teacher?
  Yes, i am. / No, i am not.
• Were they teachers?
  Yes, they were./ No ,they weren't.

Be动词的练习

• 他是医生吗
  Is he a doctor. No, he isn't.
• 他们昨天在教室吗
  Were they in the classroom yesterday?
  Yes,they were.
• 他们昨天不在教室
  They weren't in the classroom yesterday.