單項(xiàng)選擇題The evaporating pressure in R22 vapor compression refrigeration plant should be () atmospheric.

A.below
B.above
C.equal to
D.much larger than


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1.單項(xiàng)選擇題The primary task of the compressed air system is to deliver the starting air necessary for ()

A.starting the ME
B.starting the emergency electric alternator
C.driving the main turbine
D.driving the turbocharger

2.單項(xiàng)選擇題The starting air bottle should be pumped up to maximum pressure by the () before start of the engine.

A.air compressor
B.refrigeration compressor
C.vacuum pump
D.purifier

4.單項(xiàng)選擇題When distilling salt water the cooling water discharging from the distiller is fed back to evaporator as feed water ().

A.to cut down the amount of cooling water needed
B.to prevent an excess amount of cooling water from being discharged to the bilges
C.to supply hot water to the evaporator for more economical operation
D.None of the above is tree

5.單項(xiàng)選擇題When distilling sea water the cooling water discharging from the distiller is fed back to evaporator as feed water ().

A.to decrease scale formation
B.for better cooling effect
C.for more economical purpose
D.to raise vacuum