题目

--What are you going to do this afternoon? -- I am going to the cinema with some friends. The film ____ quite early, so we ____ to the bookstore after that.  A. finished; are going              B. finished; go        C. finishes ；are going             D. finishes; go 答案：C一批产品中，有n件正品和m件次品，对产品逐个进行检测，如果已检测的前k个均为正品，那么第k+1次检测的产品为正品的概率为 ________．