题目

Teamwork is very important in modern society. ______ an effective team member, you need to develop a team attitude.   A. Become                B. Becoming                 C. Having become         D. To become 答案：D本小题满分12分）设M是由满足下列条件的函数f (x)构成的集合：①方程f (x)一x=0有实根；②函数的导数满足0＜＜1.(1)若函数f(x)为集合M中的任意一个元素，证明：方程f(x)一x=0只有一个实根；（2）判断函数是否是集合M中的元素，并说明理由；(3)设函数f(x)为集合M中的任意一个元素，对于定义域中任意，证明：