单项选择题
A.Distillation is the process of boiling seawater to produce vapor which is condensed into fresh water
B.Evaporation is the second part of the distillation process where brine is removed
C.Brine is the result of condensed sea water vapor
D.Distillate is the product resulting from the evaporation of fresh water vapor
单项选择题 The amount of moisture in a given sample of air, when compared with the amount of moisture the air could hold if totally saturated at the existing temperature of the sample, is called （）.
单项选择题 The purpose of an air compressor unloading device is to （）
单项选择题 Personnel working with refrigeration systems, and subject to the exposure of refrigerants should wear （）.