题目

根据短文内容，从A、B、C、D四个选项中选取正确答案填空。A Two students of the World Wide Friends Club write to their friends on the Internet. Hello, friends! My 1 is Andy. I have black hair and I 2 glasses. My friends say I am cool with them. I am in 3 this year. I like all my lessons, 4 I'm not good at Maths. I love football very much. I often play football with my classmates. 5 are all nice. I love them. Hi, I 6 Mary. I study at a middle school. I am thirteen years old. I 7 black hair and brown eyes. This is my classroom. There are 50 small 8 and chairs in it. On the b一个足球单价a元，一个篮球b元．3a+2b表示：______．