单项选择题
A.overheated compressor bearings
B.excess lube oil viscosity
C.carbon deposits on the compressor piston rings
D.wax crystals forming in the lubricant
单项选择题 The centrifugal pump component responsible for converting the mechanical energy of the liquid being pumped, to that of kinetic energy is the （）.
单项选择题 In a refrigeration system, foaming of the crankcase oil may cause the （）.
单项选择题 Excessive scale formation in a distilling plant may result from （）.