单项选择题
A.Absorb erosion of high velocity discharge stream
B.Seal pump shaft against entry of air
C.Isolate the discharge side from the suction side
D.Dampen the turbulent discharge flow
单项选择题 If air at 95℃ dry bulb temperature and 50% relative humidity is conditioned to 75℃ dry bulb temperature and 50% relative humidity, it is an example of （）.
单项选择题 Which of the following descriptions best identifies the operating principal of a flash-type evaporator?（）
单项选择题 Which of the listed conditions can lead to cavitation气穴in a centrifugal pump?（）