电气设备中保护接地与保护接零作用是防止（）。
A.短路
B.触电
C.断路
参考答案：B
--- Mum, I’ve at last passed the final exam．
--- ________
A．Congratulations!
B．That’s all right．
C．Good luck．
D．Really good．
—We can’t climb the mountains the bad weather.
—What a pity !
A．because
B．because of
C．so
D．as
