动力转向系统有()种型式。
A、手动式
B、气压式
C、机械式
D、电动式
E、液压式
F、油压式
参考答案:B, D, E
( (本小题满分13分)
已知函数f(x)=(a-1)x+aln(x-2),(a<1).
(1)讨论函数f(x)的单调性;
(2)设a<0时,对任意x1、x2∈(2,+∞),<-4恒成立,求a的取值范围.
What moved us most was that some ordinary people volunteered to help those ______ in the storm in Beijing.
A.catching
B.having caught
C.to be caught
D.caught