单项选择题
A （） boiler is an auxiliary boiler sometimes included in a steamships installation for supplying steam to auxiliaries in port.
A.monkey B.donkey C.waste heat D.main
单项选择题 Between the steam dram and the smaller water dram below, large numbers of smaller diameter （） tubes are fitted.
单项选择题 The safety valve should be （） in the presence of C/E and Surveyor.
单项选择题 The safety valves are mounted in pairs to （） the boiler against overpressure.
