题目

—Could you tell me __________? —In Xinhua Bookstore. A . where you bought the book B . where did you buy the book C . where do you buy the book 答案：A一束与镜面成60°角的光线射到平面镜上，反射角的大小为__;一束光垂直射到水面上，入射角为__，折射角为__。