单项选择题
A.mechanical energy to kinetic energy to potential energy
B.mechanical energy to potential energy to kinetic energy
C.potential energy to mechanical energy to kinetic energy
D.kinetic energy to mechanical energy to potential energy
单项选择题 If an operating bilge pump is developing good vacuum, but is unable to discharge any water, which of the following problems is the most probable cause?（）
单项选择题 The sudden reduction of pressure occurring within the crankcase of a refrigeration compressor during starting causes the （）.
单项选择题 One of the consequences in continuing to operate a centrifugal bilge pump with the discharge valve closed, is that the （）.