room and pillar mining

例句：

1. 1. The company is exploring new room and pillar mining techniques to increase efficiency.
   该公司正在探索新的房间和支柱开采技术以提高效率。
2. 2. The pillar mining operation has been shut down due to safety concerns.
   由于安全担忧，柱子开采作业已被关闭。
3. 3. The mine manager discussed the potential risks associated with room and pillar mining.
   矿场经理讨论了与房间和支柱开采相关的潜在风险。