单项选择题
A.after TDC B.before TDC C.after BDC D.before BDC
For an ordinary four-stroke engine the inlet valves ope...
单项选择题For an ordinary four-stroke engine the inlet valves open （）
For an ordinary four-stroke engine the exhaust valves o...
单项选择题For an ordinary four-stroke engine the exhaust valves open （）.
For an ordinary four-stroke diesel engine the exhaust v...
单项选择题For an ordinary four-stroke diesel engine the exhaust valves close （）.
