单项选择题 A flash-type evaporator discharges heated seawater into a chamber that is maintained at a pressure than the vapor pressure of the entering heated seawater, and subsequently the flashed water vapor thereby produced（）

单项选择题 Before the sludge in a purifier is ejected,（）

单项选择题 A centrifuge of which the bowl is arranged as the upper and lower parts separate discharges the sludge（）