gear in train

例句：

1. 1. The train's gear is designed to make thejourney smoother.
   火车的齿轮设计是为了使旅程更加顺畅。
2. 2. The engineer had tochange the gear in the train to avoida collision.
   工程师不得不更换火车上的齿轮以避免碰撞。
3. 3. The train was delayed due toa gear failure on the tracks.
   由于轨道上的齿轮故障，火车延误了。