reverse a swap

例句：

1. 1. The car reversed into the parkinglot.
   汽车倒进了停车场。
2. 2. Shereversed the order ofthe letters in the sentence.
   她把句子中字母的顺序颠倒了。
3. 3.The teacher reversed the class to makea presentation.
   老师把班级调换位置以便做演示。