单项选择题

Which of the following statements is true concerning centrifugal pumps?（）

A.They are particularly suited for pumping high viscosity fluids
B.They are started with the discharge valve opened
C.The flow of liquid is developed by imparting energy due to the rotation of an impeller
D.They are always mounted in a horizontal position

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单项选择题The temperature of the refrigerant in the evaporator coil depends mostly upon the （）.

A.refrigerant pressure in the evaporator
B.cooling water temperature to the condenser
C.heat load in the refrigerator compartment
D.solenoid valve in the liquid line

单项选择题Refrigerant is circulated through a refrigeration system by the （）.

A.compressor
B.condenser
C.expansion valve
D.evaporator

单项选择题The type of gauge most commonly used to measure pressure is the （）.

A.bimetallic type
B.diaphragm type
C.bourdon tube type
D.resistance-temperature type

单项选择题When refrigerant leaves the receiver, it flows next on to the （）.

A.evaporator coils
B.liquid strainer
C.compressor
D.condenser

单项选择题A compound gauge is typically installed on the （）.

A.suction side of a bilge pump
B.exhaust manifold of an auxiliary diesel
C.discharge line from an air compressor
D.chemical feed tank of an evaporator