单项选择题
Differential pressures can be measured with the use of a （）.
A.diaphragm type gage B.pressure transducer C.manometer D.All of the above
单项选择题 The function of a centrifugal pump double volute casing is to （）.
单项选择题 Dirt should not be allowed to contaminate a grease lubricant because the （）.
单项选择题 The presence of bubbles in a refrigeration system liquid line may （）.
