单项选择题
A.steam plants, electric motors and compressed air
B.diesel engine, hydraulic machinery and compressed air
C.steam plants, electric motors and hydraulic machinery
D.diesel engines, steam plants and hydraulic machinery
单项选择题 Mooring winches are often combined with （） units so that one prime mover drives both.
单项选择题 Due to the large amount of heat picked up by the air in boiler and engine rooms, it would be （） to maintain ambient conditions within the comfort zone by air conditioning.
单项选择题 A(n) （） is a mechanical attack on the metal surface which may be due to a disturbance in the flow of the water over the blade of the propeller.