单项选择题
A.improve power factor B.reduce voltage oscillation C.increase the insulation of circuits D.eliminate regenerated magnetic fields
What is head tank in the closed cooling water system us...
单项选择题What is head tank in the closed cooling water system used for?（）
A.for the release of air from the cooling water B.providing expansion room for heated cooling water C.a place for implementing water and water treatment agent D.all of the above
According to the principle of four stroke diesel engine...
单项选择题According to the principle of four stroke diesel engine, what is the number of its efficient work stroke per revolution?（）
A.1/2 B.1 C.2 D.3
What type of electric motor is most commonly used on bo...
单项选择题What type of electric motor is most commonly used on board ship?（）
A.non-synchronous electric motor B.synchronous electric motor C.fully enclosed electric motor D.watertight electric motor
