有外壳的

例句：

1. 1. The crab has a hard shell to protect its soft body.
   螃蟹有硬壳来保护它的柔软身体。
2. 2. The tree's trunk is covered in a thick layer of bark, which is the tree's outer shell.
   树的树干上覆盖着厚厚的一层树皮，那是树的外层壳。
3. 3. The scientist removed the outer shell of the egg and observed the developing embryo inside.
   科学家移除了蛋的外层壳，观察了正在发育的胚胎。