edging stone

例句：

1. 1. The river is lined with smooth,grey stones that are easy to walk on.
   这条河沿岸铺满了光滑的灰色石头，走在上面很舒适。
2. 2. The buildersused these stones to create a beautiful gardenborder.
   建筑者用这些石头建造了一个美丽的花园边界。
3. 3. The edge of the cliff iscovered in sharp, jagged rocks thatmake it difficult to climb.
   悬崖的边缘覆盖着尖锐、参差不齐的岩石，这使得攀爬变得困难。