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 （）.
单项选择题 When refrigerant leaves the receiver, it flows next on to the （）.
单项选择题 A compound gauge is typically installed on the （）.
