trunk pipe line

例句：

1. 1.The company's mainline pipeline runs through the heart of the city.
   该公司的主干管道线穿过市中心。
2. 2. The engineer used a special tool to repair the mainline pipe line.
   工程师使用一种特殊的工具来修理主线管道。
3. 3.Mainline pipelines are essential for transporting oil and gas across large distances.
   主线管道对于运输石油和天然气跨越大距离至关重要。