【题目】给下列句子选择恰当的答语。
A. Yes, I was.
B. They are Helen's.
C. They are playing games.
D. Yes, it is.
E. Hello, Yang Ling.
1.Hello, Liu Tao. (_____)
2.Were you at school yesterday? (_____)
3.Is this your book? (_____)
4.Whose books are these? (_____)
5.What are they doing? (_____)