单项选择题
Constant superheat is maintained at the evaporator outlet of a refrigeration coil by a（）
A.solenoid valve B.low pressure cutout switch C.king valve D.thermal expansion valve
单项选择题 Hot gas bypass is one of the methods used to （）
单项选择题 Thermostatic expansion valves can be adjusted for （）
单项选择题 The receiver used in a refrigeration system（）
