简述影响爆炸的因素有哪些？
参考答案：原始温度和压力、惰性气体含量、容器大小、火源的性质。
I will let you know as soon as he _____. [ ]
A. comes back
B. will come back
C. is coming back
D. come back
电焊机一次侧电源线不得大于（）。
A、3m
B、5m
C、8m
