—You look upset.What's the matter?

—I had my proposal ________ again.(2011·江苏)

A．turned over

B．turned on

C．turned off

D．turned down

在对叉车进行二级维护保养时，应检测（），以确定是否需要更换活塞环。

A.液压缸

B.压强

C.气缸压

D.气体