题干
— Thank you for your coffee. I'm afraid I have to be off now.
— OK, _______.
A：Go slowly
B：All right
C：Sounds great
D：See you
答案(点此获取答案解析）
D
— Thank you for your coffee. I'm afraid I have to be off now.
— OK, _______.
A：Go slowly
B：All right
C：Sounds great
D：See you
在
上为减函数，则实数
的取值范围
．