洞穴

例句：

1. 1. The cave is dark and damp.
   这个洞穴又黑又潮湿。
2. 2. They explored the caves in the mountains.
   他们探索了山区的洞穴。
3. 3. The cave was filled with stalactites and stalagmites.
   洞穴里充满了石笋和石柱。