单项选择题
The humidity of the atmosphere can be determined by the use of the（）
A.anemometer B.potentiometer C.manometer D.psychrometer
单项选择题 In a centrifugal Freon refrigeration system, the overall capacity of the system is increased by（）
单项选择题 The main distribution duct in an air conditioning system which contains the cooling coils and filters is called the（）
单项选择题 If a compressor runs continuously, the cause might be a（）
