单项选择题
The scale trap is located between the （）
A.king valve and the expansion valve B.solenoid valve and expansion valve C.evaporator and receiver D.compressor and evaporator
单项选择题 The relief valve is located on the（）
单项选择题 If the compressor-discharge temperature is higher than the receiver temperature（）
单项选择题 If the head pressure is too high,（）
