单项选择题
Because of the reduced （） in the distillation system, some of the sea water boils as it flows through the tubes of the evaporator.
A.pressure B.temperature C.density D.volume
单项选择题 In a vacuum distillation system, the case is the higher the pressure, （）.
单项选择题 A hydraulic machine is one that uses （） to do work.
单项选择题 If oil density were greater than water’s, the oil separator （）.
