单项选择题
A.open B.close C.remain in its position D.flood the evaporator with refrigerant
Black smoke coming from a boiler can be caused by （）.A....
单项选择题Black smoke coming from a boiler can be caused by （）.
A.low water level B.low oil pressure C.excessively high fuel pressure D.an improper air/fuel ratio
Which will cause the high pressure cutout to stop the c...
单项选择题Which will cause the high pressure cutout to stop the compressor in a R-22 system?（）
A.Condenser leakage B.A shortage of liquid refrigerant C.Excessive frost on the evaporator D.Not enough condenser cooling water
Insufficient refrigerant in a refrigeration plant may r...
单项选择题Insufficient refrigerant in a refrigeration plant may result in （）.
A.high discharge pressure B.frosting of the crankcase C.high temperature of the overboard water D.low suction pressure of compressor
