smoothing time-series data

例句：

1. 1. The car's engine is smoothing down as it accelerates.
   汽车加速时发动机正在变得平稳。
2. 2.The road was smoothing out after the rain.
   雨后，路面变得平坦了。
3. 3.The paint job on the car is smoothing nicely.
   汽车上的油漆工作得非常好，正在变得光滑。