单项选择题
A.prevent the gear box from leaking B.prevent the oil from becoming inflammable C.make sure it has not become contaminated D.make sure the motor bearings are lubricated
A spur gear pump should be operated with the discharge ...
单项选择题A spur gear pump should be operated with the discharge valves （）.
A.slightly opened B.throttled C.fully opened D.halfway opened
The capacity of a centrifugal pump can be increased by ...
单项选择题The capacity of a centrifugal pump can be increased by the installation of a larger diameter impeller Another means of increasing the pump capacity is to （）.
A.increase speed B.increase the size of the cardent assembly C.reduce wearing ring clearances D.change the pump to a "close coupled" arrangement
Which of the following forms of energy is demonstrated ...
单项选择题Which of the following forms of energy is demonstrated through the process of combustion?（）
A.Chemical energy B.Mechanical energy C.Thermal energy D.Electrical energy
