如阀门打开或关闭的时间不对或根本打不开或关不住，空气无法进入，废气无法排出，因此发动机不运转。

If the valves do not open and close at the right time or at all, air cannot get in and exhaust cannot get out, so the engine cannot run.

youdao

如阀门打开或关闭的时间不对或根本打不开或关不住，空气无法进入，废气无法排出，因此发动机不运转。

If the valves do not open and close at the right time or at all, air cannot get in and exhaust cannot get out, so the engine cannot run.

youdao