设备动火前可燃气体浓度应低于爆炸下限多少为合格?
参考答案:
低于其爆炸下限浓度的25%为合格。
If I you, I would rather at home and watch TV than to the party.
A.was;stay, go
B.am;stay, go
C.were;to stay, go
D.were;stay, go
— What do you think of the Voice of China?
— I have no idea, because I it yet.
A.didn’t see
B.don’t see
C.won’t see
D.haven’t seen