单项选择题
A.horizontally mounted
B.never fitted with intake filters
C.fitted with intercoolers
D.operated in an unloaded condition at all times
单项选择题 Which of the following statements is true concerning the overall efficiency of air compressors?（）
单项选择题 The ability of an oil to separate cleanly from an oil and water mixture is referred to as its （）.
单项选择题 When the relief valve opens it discharges high pressure refrigerant vapor to the （）.