阅读理解。

1.Lin Yang: I know Yao Ming. He is great. I want to play sports with my friends.

But we don't have soccer balls, basketballs or volleyballs.

2.Liu Mei: It's very cold here, but I have only an old sweater. It's my mother's. I

need new clothes.

3.Wang Li and Wang Xia: We are sisters. We don't have a clock in our home.

We don't know the time to go to school. We don't want to be late for school.

4.Zheng Lei: Our teachers tell us, books are our friends. I want to read many books.

5.Dai Xu: My shoes are broken. My parents can't afford a new pair of shoes.

抗坏血酸结构中特有的官能团是（）.

A．C_17-α-醇酮基

B．酚羟基

C．二烯醇基

D．吡啶环

E．β-内酰胺环