单项选择题
A donkey boiler is （）.
A.one to supply steam to the main propulsion turbine B.an auxiliary boiler C.A and B D.neither A nor B
单项选择题 Safety valves on a boiler vent to the （）.
单项选择题 The boiler feed pump discharge pressure is higher than the steam drum pressure to （）.
单项选择题 If in doubt as to the true water level when a boiler is being oil-fired, you should （）.
