單項(xiàng)選擇題

A spur gear pump should be operated with the discharge valves （）.

A.slightly opened
B.throttled
C.fully opened
D.halfway opened

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單項(xiàng)選擇題

The capacity of a centrifugal pump can be increased by the installation of a larger diameter impeller Another means of increasing the pump capacity is to （）.

A.increase speed
B.increase the size of the cardent assembly
C.reduce wearing ring clearances
D.change the pump to a "close coupled" arrangement

單項(xiàng)選擇題

Which of the following forms of energy is demonstrated through the process of combustion?（）

A.Chemical energy
B.Mechanical energy
C.Thermal energy
D.Electrical energy