写出下列句子的复数形式this is my book.is that your sister?that is my baseball.is this your friend?what's this in english?

问题描述:

写出下列句子的复数形式
this is my book.
is that your sister?
that is my baseball.
is this your friend?
what's this in english?

These are our books.
Are those your sisters?
Those are our baseballs.
Are those your friends?
What are these in English?