变一般疑问句 .否定句.否定回答.肯定回答
I‘m a doctor.
依次为：Are you a doctor?I'm not a doctor.Yes,I am.No,I'm not.
You are a student.
依次为：Are you a student?You are not a student.Yes,I am.No,I'm not.
It is my ruler.
Is it your ruler?It isn't my ruler.Yes,it is.No,it isn't.