单项选择题
A.to decrease scale formation
B.for better cooling effect
C.for more economical purpose
D.to raise vacuum
单项选择题 In a vacuum boiling evaporator, the fresh water generated is pumped out by （）.
单项选择题 With a vacuum boiling evaporator, the remainder of sea water fed to the evaporator is pumped out by （）.
单项选择题 When a vacuum boiling evaporator works, the hot jacket water will pass over the tube stack and （） the sea water passing through the tubes.