单项选择题
A.monkey B.donkey C.waste heat D.main
Between the steam dram and the smaller water dram below...
单项选择题Between the steam dram and the smaller water dram below, large numbers of smaller diameter （） tubes are fitted.
A.fire B.water wall C.generating D.down comer
The safety valve should be （） in the presence of C/E an...
单项选择题The safety valve should be （） in the presence of C/E and Surveyor.
A.tightened up B.sealed up C.opened up D.unscrewed
The safety valves are mounted in pairs to （） the boiler...
单项选择题The safety valves are mounted in pairs to （） the boiler against overpressure.
A.use B.release C.protect D.effect
