39. For operating a marine boiler, which device does not belong to safety devices?
(A) Flame detector
(B) Soot blower
(C) Low-water level cut-off device
(D) Safety valves
答案:登入後查看
統計: A(117), B(580), C(138), D(159), E(0) #3003407
統計: A(117), B(580), C(138), D(159), E(0) #3003407