单项选择题
Thermostatic expansion valves can be adjusted for （）
A.suction pressure only B.head pressure only C.superheat only D.suction pressure and box temperature
单项选择题 The receiver used in a refrigeration system（）
单项选择题 The purpose of the refrigeration system low pressure cutout switch is to （）
单项选择题 A pressure drop in the liquid line of a refrigeration system may cause（）
