flat ground

例句：

1. 1. The floor is very flat and easy to clean.
   地板非常平坦，容易清洁。
2. 2. The car's tires are flat, which makes it difficult to drive.
   汽车的轮胎是扁平的，这使得驾驶变得困难。
3. 3. The ground was too flat for me to walk on comfortably.
   地面太平坦了，我走起来不舒服。