单项选择题
A.system is overcharged with refrigerant
B.system is low on refrigerant
C.discharge valves are leaking excessively
D.discharge valves are leaking slightly
单项选择题 A cargo hold has been determined to have a relative humidity of 80% and a dry bulb temperature of 80 ℃ and a dry bulb temperature of 85℃.When the hold is sealed and the dry bulb temperature decreases, the relative humidity in the space will （）
单项选择题 A purge recovery system is used in a centrifugal air conditioning or refrigeration system to （）
单项选择题 A re-heater, as used in an air conditioning system, is designed to control the （）