spare track link

例句：

1. 1. The spare tracklink is essential for emergency repairs.
   备用轨道连接对于紧急修理至关重要。
2. 2. Theengineer used the spare track link to fixthe damaged rails.
   工程师使用备用轨道连接来修复损坏的铁轨。
3. 3. The trainwas delayed due to a fault in thespare track link.
   由于备用轨道连接出现故障，火车延误了。