单项选择题
A.too much refrigerant in the system
B.oil entrained in the refrigerant
C.less than a full charge of refrigerant in the system
D.ice crystals forming in the refrigerant
单项选择题 Dual electro-hydraulic steering units usually operate （）.
单项选择题 One distinct advantage of flash type evaporators, as compared to most other evaporators, is that in a flash evaporator （）.
单项选择题 A liquid indicator sight glass is useful in determining whether or not a refrigeration system is sufficiently chargedIt is generally located in the（）.