smoothing

例句：

1. 1. The surface of the glass is very smooth.
   玻璃的表面非常光滑。
2. 2.The car's paint job was smoothed down to perfection.
   汽车的漆面被打磨得完美无瑕。
3. 3.The road was smoothing out after the rain.
   雨后，路面变得平坦了。