train diagram not in pairs

例句：

1. 1. The trainarrived at the station on time.
   火车准时到达了车站。
2. 2. He took a train tovisit his friend in another city.
   他乘火车去另一个城市看望朋友。
3. 3. The trainwhistle blew as it left the station.
   火车离开车站时鸣笛了。