题目

—______ do you go to the cinema? —On Sunday evening. A. How often             B. When C. What time              D. What 答案：B15．如图，Rt△ABC中，∠B=90°，AB=4，BC=3，AC的垂直平分线DE分别交AB，AC于D，E两点，则CD的长为$\frac{25}{8}$．