题目

 ---How do you find your physics teacher?  --- ______________.    A. In the teachers’ office.      B. By chatting on line    C. She is all right as long as you do well in the tests.    D. She is not quite herself today. 答案：C(12分)已知定义域为的偶函数. (1)求实数的值; (2)判断并证明的单调性;(3)若对任意恒成立，求实数的取值范围.