单项选择题
A.reciprocating B.diffuser C.turbine D.vane
The water level in the gauge glass when a boiler is ope...
单项选择题The water level in the gauge glass when a boiler is operating is （） when the boiler is shut down.
A.lower than B.higher than C.below D.equal to
Large pipes or （） are fitted between the steam and wate...
单项选择题Large pipes or （） are fitted between the steam and water drums to ensure good natural circulation of water.
A.fire-tubes B.furnaces C.down-comers D.soot-blowers
（） system is arranged to ensure that water can be drawn...
单项选择题（） system is arranged to ensure that water can be drawn from any tank or the sea and discharged to any other tank or the sea as required to trim the vessel.
A.The domestic water B.Bilge water C.Oil transfer D.The ballast
