依据PB阅读理解选择:. ________ is not the purpose of a flywheel.
A.
It reduces vibration by smoothing out the power stroke as each cylinder fires
B.
It is mounting surface used to bolt the engine up to its load
C.
Some diesel flywheel has gear teeth around its perimeter that allow the starting motors to engage and crank the engine
D.
It converts the up and down motion of the piston into a rotary motion