砾石

例句：

1. 1. The road was covered in a layer of gravel.
   这条路上铺满了一层碎石。
2. 2. The builders used gravel to level the ground.
   建筑工人用碎石来平整地面。
3. 3. Gravel is a natural material that can be found on many surfaces.
   砾石是一种自然材料，可以在许多表面上找到。