smooth plain packing

例句：

1. 1. The surface of the stone is very smooth.
   这块石头的表面非常光滑。
2. 2.The car's paint job is so smooth that it looks brand new.
   这辆车的漆面处理得如此光滑，看起来就像全新的一样。
3. 3. The floor was smooth and polished to perfection.
   地板被打磨得非常光滑，完美无瑕。