把下面的句子变为复数形式
问题描述：
把下面的句子变为复数形式
1.This is my sister
2.That is his brother
3.what is that
4.Ls this your friend
5.that isn't a book
答
1.This is my sister
These are my sisters.
2.That is his brother
Those are his brothers.
3.what is that
What are those?
4.Ls this your friend
Are these your friends?
5.that isn't a book
Those aren't books.