底冰

例句：

1. 1. The ship was anchored in the middle of a large bay with a layer of slushy base ice.
   这艘船停泊在一个大海湾的中心，底部覆盖着一层松软的冰。
2. 2. The polar bears were swimming on the base ice of the frozen lake.
   北极熊们在冻湖的底部冰面上游泳。
3. 3. The scientists used a drone to survey the base ice for signs of melting.
   科学家们使用无人机对底部冰面进行了勘测，以寻找融化的迹象。