bolthole circle

例句：

1. 1.The ancient temple was abolished and replaced by a modern building.
   这座古老的寺庙被一座现代建筑所取代。
2. 2. The scientist found a bolthole circle in the cave.
   这位科学家在洞穴里发现了一个洞窟圆形。
3. 3.The archaeologists discovered a bolthole circle that dates back to the Neolithic era.
   考古学家发现了一个可以追溯到新石器时代的洞窟圆形。