subterranean pipe line

例句：

1. 1. The subterranean tunnel is the main route to the city center.
   这条地下隧道是通往市中心的主要路线。
2. 2. The construction of the subterranean pipeline has been completed.
   地下管道的建设已经完成。
3. 3. The geologists are studying the subterranean formations in the area.
   地质学家正在研究该地区的地层构造。