题目

若函数在区间单调递增，则的取值范围是 （ ）A. B. C. D. 答案：【答案】D【解析】试题分析：，∵函数在区间单调递增，∴在区间上恒成立．∴，而在区间上单调递减，∴．∴的取值范围是．故选：D．___ you know the rules of swimming, you will be able to swim well.         A.Before     B.While       C.Though      D.Once