lighthouse cavity

例句：

1. 1. The lighthouse was built to provide a safe harbor for ships in the night.
   灯塔建于夜间为船只提供安全的避风港。
2. 2. The lighthouse's cavity is filled with sand and rocks, which helps it stay afloat.
   灯塔的内部充满了沙子和岩石，这有助于它保持浮力。
3. 3. The lighthouse's cavity is also used as a storage area for supplies and equipment.
   灯塔的内部还用于存放物资和设备。