raw bark

例句：

1. 1. The tree's raw bark is a rich source of nutrients for the forest ecosystem.
   这棵树的生皮是森林生态系统丰富的养分来源。
2. 2.The old tree had been left with only its raw bark remaining.
   那棵老树只剩下了它的生皮。
3. 3. The woodworker carefully stripped off the raw bark to reveal the inner structure.
   这位木工仔细地剥去了生皮，露出了内部的结构。