單項選擇題

A.the suction and discharge valves
B.tools and equipment served by compressed air
C.air line reducing valves
D.all of the above

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A.Moisture separator
B.Vacuum breaker
C.Lubricator
D.Non-return valve

A.rate of doing work
B.amount of force needed to overcome friction
C.amount of work accomplished
D.distance through which an object is moved