题目内容
(请给出正确答案)
[主观题]
The cylinder oil is pumped into the cylinder (via non-return valves) when the piston rings
The cylinder oil is pumped into the cylinder (via non-return valves) when the piston rings pass the lubricating orifices, during ______.
A.the upward stroke
B.the downward stroke
C.the power stroke
D.the suction stroke
如搜索结果不匹配,请 联系老师 获取答案