题目

If he had worked harder, he _________. A. would succeed                 B. had succeeded C. should succeed                 D. would have succeeded 答案：D已知函数（）.（1）证明：当时，在上是减函数，在上是增函数，并写出当时的单调区间；（2）已知函数，函数，若对任意，总存在，使得成立，求实数的取值范围.