gravel by nature

例句：

1. 1. The road was covered in gravel asit had been recently washed by the rain.
   这条道路因为最近被雨水冲刷过，覆盖着碎石。
2. 2. Thebuilders used gravel tomake the foundation of the house.
   建筑工人用碎石来建造房子的基础。
3. 3. The gravel path led to a smallpond at the edge of the forest.
   砾石小径通向森林边缘的一个小池塘。