单项选择题
Where are the zinc plates located?（）
A.saltwater side of the condenser B.refrigerant side of the condenser C.in the evaporator coils D.in the suction strainer
单项选择题 The device used for low-pressure control and high-pressure cutout on a compressor is called a（）
单项选择题 The purpose of the purge valve at the top of the condenser in a refrigerating system is to（）
单项选择题 What is the purpose of sub cooling R-12 in the condenser?（）
