A.cause of salt contaminationB.location of salt water c……

单项选择题If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.

A.refrigerant overcharge
B.overfeeding by the expansion valve
C.a restricted suction strainer
D.due to short cycling of the compressor

单项选择题If the viscosity of the liquid being transferred remains constant as the discharge pressure increases, the rotary pump （）.

A.capacity will increase
B.capacity will decrease
C.suction pressure will increase
D.suction pressure will decrease

单项选择题On tank vessels equipped with power operated cargo tank valves, the type of power operator most commonly used is （）.

A.hydraulic
B.electric
C.steam
D.diesel

单项选择题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.

A.increase the amount of cooling water to the condenser
B.decrease the amount of cooling water to the condenser
C.add more refrigerant to the system
D.remove some refrigerant from the system

单项选择题Which of the following statements is correct concerning heat transfer?（）

A.Heat is given off from a high temperature region known as a heat sink
B.Heat transfer rate is affected most by the size of the heat sink involved
C.Heat transfer rate is affected most by the temperature difference between the heat source and the heat sink
D.Heat transfer by radiation will occur only by mass motion of a fluid substance