题目

I have bought such a watch _______ was advertised on TV.A. that         B. which          C. as         D. it 答案：C 解析: 当先行词被such修饰时,引导定语从句的关系代词要用as. As在本从句中作主语.如图，△ABC中，∠ACB=90°，AB=5，AC=4，若把Rt△ABC绕直线AC旋转一周，则所得圆锥的侧面积等于（　　）A．6πB．9πC．12πD．15π