题干
当你想跟Black先生通电话时，应说：
A：Hello! Are you Mr. Black?
B：Hello! I'm Peter. Who are you?
C：Hello! May I speak to Mr. Black?
D：Hello! Where's Mr. Black?
答案(点此获取答案解析）
C
，试求小明家圆形花坛的面积．