单项选择题
To add refrigerant to the high side of an air conditioning system, you should introduce the refrigerant through the （）.
A.discharge service valve as a vapor B.suction service valve as a liquid C.charging valve as a liquid D.condenser purge valve as a vapor
单项选择题 When adding oil to a refrigeration system, precautions must be taken to ensure that （）.
单项选择题 In a refrigeration system, if the cooling water to the condenser fails, the（）.
单项选择题 Accidental flooding of the engine room bilges by the bilge main is prevented by （）.
