单项选择题

To operate a centrifugal fire pump at reduced capacity, you should （）.

A.readjust the relief valve
B.throttle the suction line
C.throttle the discharge valve
D.open the priming line

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单项选择题

An AC synchronous transmission type remote steering control system consists of a （）.

A.transmitter at the steering station and a receiver at the steering engine
B.reversible motor at the steering station geared to the steering pumps
C.small induction motor on the bridge which controls the redder through pulleys
D.variable displacement hydraulic pump driven by a reversible DC motor

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In which of the areas listed would you expect to find the highest salt concentration in a flash evaporator?（）

A.Distiller air ejector cooling medium
B.Saltwater heater discharge
C.First-stage internal feed box
D.Second-stage internal feed box

单项选择题

The component of a refrigerating system in which the refrigerant vaporizes and absorbs heat is known as the （）.

A.condenser
B.vapor generator
C.accumulator
D.evaporator