After they ________ their tents, they went off to look for something to eat.   [ ]

A. set up    

B. put on      

C. put up    

D. set out

因供电系统故障而导致加弹机突然失电时，在切断主电源开关后，我们仍然需要（）。

A.关闭变频器电源开关

B.关闭控制电脑电源开关

C.关闭热箱电源开关

D.关闭主要马达电源开关