单项选择题
A.compensate for major leaks in the system
B.maintain the original fluid viscosity
C.allow for changes in pressure and temperature within the system
D.assure constant fluid temperature
单项选择题 To avoid damaging the components of a printed circuit board when testing it with a DC volt-ohmmeter, you should （）
单项选择题 The heated feedwater entering any flash chamber of a flash-type evaporator will（）
单项选择题 In a refrigeration system, which of the following statements describes the actions occurring when a solenoid valves, used in conjunction with an unloader head is energized?（）