题目

Come and see me whenever ___________. A you are convenient                    B you will be convenient C it is convenient to you                D it will be convenient to you 答案：C下列说法不正确的是(　　)A. 炼铁需要用到石灰石 B. 钠钾合金可用作核反应堆热交换剂C. 工业上可用铁质容器存放浓硫酸 D. 用超纯硅制造光导纤维