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單項選擇題

When installed for bilge pumping or ballast duty, centrifugal pumps require a （） to remove air from the suction pipe.

A.air chamber
B.head lank
C.primer
D.prime mover

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單項選擇題

Water enters the rotating impeller through the entry, known as “（）”, at the centre.

A.eye
B.hole
C.balance holes
D.opening

單項選擇題

Which one is not the normal operation for boiler shutdown?（）

A.Carry out soot blowing if permissible
B.Change fuel supply to diesel oil
C.Close steam stop valves on boiler when pressure is reduced
D.Drain boiler empty when it has cooled down