单项选择题
A.freeze on the expansion valve seat and reduce the flow of liquid refrigerant
B.emulsify the oil in the condenser
C.freeze in the king valve
D.clog the oil trap
单项选择题 Why will a two stage flash type distilling plant tend to operate more efficiently when operating in cold seawater?（）
单项选择题 Moisture is removed from a refrigeration system by（）.
单项选择题 A centrifugal pump vibrates excessively during operationUpon disassembling the pump it is found that the impeller is out of balanceWithout an available spare, you should （）.