*Some medium and high-speed diesel engines require reduction gear units to provide a useful propeller speed.1n most reduction gears, the bull gear ____.
A.
must churn(搅拌)the oil in the sump
B.
is connected to the propeller shaft
C.
is driven at the highest r/min
D.
compensates(补偿) for alignment variations between the engine and pinion gear(小齿轮)