单项选择题
A.A capstan B.A hold C.A warp end D.A mooring drum
（） provides the head or pressure to supply the domestic...
单项选择题（） provides the head or pressure to supply the domestic water where required.
A.The compressed air B.The compressing air C.The transfer pump D.The head tank
Under rotary pumps are the gear, （）, cam-and-piston and...
单项选择题Under rotary pumps are the gear, （）, cam-and-piston and screw types.
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
