1.He is an English teacher .------He isn't an English teacher .
2.Is it a new stamp?---------It is a new stamp.
3.Are you Miss Green?---------No,I'm not.(第二人称变成第一人称）
4.Is that your coat?---------Yes,it is.(一楼是错的,这里只能用it)
5.This is a nice picture.---------This isn't a nice picture.
一楼的注意啊,你的isn't有两个打成isn's,注意细节啊
楼主,祝你学好英语（这些题很简单啊,要多思考）