短语词组短語oil passage slot 油通道縫隙oil guiding slot 導油溝piston oil slot 活塞油槽Oil -returning slot 廻油槽;機油泵敺動齒輪pinion with oil slot 油槽齒輪軸errors of distributing oil slot 分配油槽誤差double slot oil piston ring 雙槽油環 返回 oil slot