----Three problems are too hard to     . Will you give me some advice?

----There are many ways. The mostt important is to have a careful plan.

A．work out

B．look out

C．hand out

D．break out

不适于输送易燃易爆气体压缩机，多用于输送空气的离心式鼓风机是（）轴位移保护装置。

A.液压式

B.哨笛式

C.触点式

D.电磁式