DR track line

例句：

1. 1. The DR track line runs through the city center.
   这条轨道线穿过市中心。
2. 2. The engineer used a laser to mark the DR track line.
   工程师用激光标记了轨道线。
3. 3. The DR track line is crucial for the train's operation.
   轨道线对于火车的运行至关重要。