单项选择题
Which of the listed conditions can lead to cavitation气穴in a centrifugal pump?（）
A.Vapor pockets formed in the suction flow stream B.Rough easing volute surfaces C.Worn wearing rings D.Heavy fluid in the flow stream
单项选择题 A centrifugal bilge pump requires priming （）.
单项选择题 The process of removing moisture from air is known as（）.
单项选择题 The heat gained per pound of refrigerant in the evaporator is known as the（）.
