单项选择题
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
The defective place in the furnace should be （） with fi...
单项选择题The defective place in the furnace should be （） with fire bricks.
A.paved B.cleaned C.welded D.dismantled
