－I'm afraid that I couldn't pass the examination.

－As a student，you need to believe in yourself________you have the ability to achieve any________goal.

A．knowing；to be set

B．knowing；set

C．known；setting

D．known；to be set

以下属于水工建筑物可变作用荷载的是（）。

A.结构自重

B.地应力

C.预应力

D.扬压力