flat positive peak

例句：

1. 1. The floor is very flatand easy to clean.
   地板非常平坦，容易清洁。
2. 2. The car was parked ona flat surface.
   汽车停在一个平坦的表面。
3. 3.The flat roof of the house provides excellentshade.
   房子的平顶提供了极好的遮阳效果。