单项选择题
To add refrigerant to the low side of an air conditioning system, the refrigerant should be introduced through the （）
A.suction service valve as a vapor B.suction service valve as a liquid C.discharge service valve as a vapor D.charging valve as a liquid
单项选择题 Which of the fluids listed is normally used to condense the primary refrigerant in a shipboard central air conditioning system?（）
单项选择题 The effective temperature of air is dependent upon（） Ⅰ.relative humidity Ⅱ.air velocity
单项选择题 When air is at its dew point it is at its（）
