题目

圆周上有四个等分圆周的点,从这四个点中任取三点为顶点作一个三角形,则所作的三角形是等腰直角三角形的概率是(    )A.        B.           C.        D.1 答案：解析：考查古典概型的概率计算公式,本题中基本事件的个数比较多,可用枚举法列出所有的基本事件.答案：D We were all surprised when she made it clear ________ she would retire soon. A. whether          B. that                C. when            D. what