steam tracing line

例句：

1. 1. The steam tracing line is used to trace the path of a steam engine.
   蒸汽追踪线用于追踪蒸汽引擎的路径。
2. 2. The steam tracing line helps us to understand the movement of water molecules.
   蒸汽追踪线帮助我们理解水分子的运动。
3. 3.The steam tracing line was used to map out the terrain before the construction of the new bridge.
   蒸汽追踪线被用来在建造新桥之前绘制地形图。