单项选择题
The low pressure side of a refrigeration system is considered to exist from the （）.
A.expansion valve to the compressor B.receiver to the expansion coil C.expansion valve to the evaporator D.condenser to the expansion valve
单项选择题 If the electric motor driving an air compressor fails to start, the cause may be a （）.
单项选择题 The refrigerant gas returning to the compressor should be （）.
单项选择题 The vacuum maintained in the salt water feed heater shell of a flash-type evaporator is generally accomplished by （）.
