低压电器产生直流电弧从燃烧到熄灭是一个暂态过程，往往会出现（）现象。
A、过电流
B、欠电流
C、过电压
D、欠电压
参考答案：C
If an inflatable liferaft is to be released manually，where should the operating cord be attached before throwing the raft overboard?（）
A.Do not attach the cord to anything but throw it overboard with the raft container
B.Attach the cord to a fixed object on the ship
C.You should stand on the cord
D.Attach the cord to the special pad eye on the raft davit launcher
CRH1A型动车组如果（）个ACM不工作，5辆车HVAC工作在减载模式1，其它处于正常模式，10分钟一个循环。
A.1
B.2
C.3
D.4
