flat sliding

例句：

1. 1. Thefloor is very flat and easy to clean.
   地板非常平坦，容易清洁。
2. 2. The carwas parked on a flat surface.
   汽车停在一个平坦的表面。
3. 3. The table is flatenough for both of us to sit onit.
   桌子足够平坦，我们可以同时坐在上面。