line idle

例句：

1. 1.The train was so crowded that there was no room for line idle.
   火车非常拥挤，没有空间供线路空闲。
2. 2. The engineer checked the line idle to ensure everything was running smoothly.
   工程师检查了线路空闲，以确保一切运行顺畅。
3. 3. During maintenance, the line idle was used to prevent traffic congestion.
   在维护期间，线路空闲被用来防止交通拥堵。