单项选择题
Excessive scale formation in a distilling plant may result from （）.
A.poor distillate quality B.reduced evaporator capacity C.low brine concentration D.improper vacuum regulation
单项选择题 Foaming of the oil in a refrigeration compressor crankcase is caused by （）.
单项选择题 Which of the listed characteristics can be applied to R- 12 vapor?（）
单项选择题 The percentage of impurities in a specific fuel oil sample is determined by （）.
