题目

If everyone makes a contribution _______the environment, our hometown Nanjing will become more beautiful. A. to protect         B. in protecting      C. to protecting         D. for protecting 答案：C函数的定义域为开区间,导函数在内的图象如图所示,则函数在开区间内有极小值点(　　)       A．个       B．个     C．个           D．个