Mr.Li（ is ）my teacher.
This(is )my bag.
You( are )a teacher.I( am )a student.
-I( am )Peter( Are )you John?Yes,I( am ).
My MOm and I( are )fine.
Mr.Li and I( are )at home.
My mom( is )a teacher.I( am )her student
教你一个方法：一单am ;二单are,三单is ;复数are
即第一人称单数用am,第二人称单数用are,第三人称单数用is,复数全是用are