单项选择题
A.mixed-flow pump
B.axial-flow pump
C.centrifugal pump
D.displacement pump
单项选择题 Sediment collects in a tubular purifier ().
单项选择题 In an oil cooler circulated by sea water, the oil is at a larger pressure the result being that any leak in the cooler will mean a loss of ().
单项选择题 In (), hot diesel engine jacket water passes over the stack and heats the sea water passing through the tubes.