防爆电气设备入井前，应经过哪些检查全格并签发合格证后，方可入井？
参考答案：
应检查其“产品合格证”、“煤矿矿用产品安全标志”、“防爆合格证”及安全性能。
The boss _______ company I worked in two years ago has ______ in solving such kind of problem.
A．whose; many experiences
B．who; many experiences
C．whose; much experience
D．which; much experience
燃（煤）气着火后如何扑救？
