v.发动机旋转；加快速度
n.发动机的旋转
Don't rev the engine so hard. 别让发动机转得太快。
If you rev up your engine too fast,you may damage it. 如果你使发动转速太快，就会把它弄坏的。
The engine was doing a steady 4000 revs (per minute). 引擎达到（每分钟）4000转的恒定转速。
