单项选择题
On a large diesel engine installation, crankshaft axial alignment is maintained by the （）
A.piston rod guides B.engine thrust bearing C.crosshead bearing D.main shaft flexible coupling
单项选择题 A piston is said to be at top dead center when it is （）
单项选择题 During which of the listed piston stroke of a four-stroke/cycle diesel engine, is the piston moving downward?（）
单项选择题 A piston is at bottom dead center when it is（）
