unleached wood ashes

例句：

1. 1. The ancient ruins of the city are preserved in their original state by the conservation efforts.
   城市的古老遗迹通过保护工作得以保存。
2. 2. The fire left behind a lot of unleached wood ashes that were difficult to clean up.
   火灾留下了许多未风化的木材灰烬，清理起来很困难。
3. 3.The archaeologists found traces of unleached wood ashes in the soil, indicating the presence of ancient structures.
   考古学家在土壤中发现有未风化的木材灰烬的痕迹，表明存在古代建筑。