----Do you hear that Mary quarreled with Lily this morning?

----Are you sure?But they acted_____nothing had happened.

A．as if

B．as long as

C．even if

D．so that

GN2系列隔离开关动触头采用铜制刀闸片，闭合时静触头夹在动触头两刀闸片之间，其目的是（）。

A.增加接触电阻

B.增加接触面积

C.增加接触压力

D.增强动稳定性