fly stair

例句：

1. 1. The old man is trying to climb the stairs to reach his office.
   老人正试图爬楼梯去他的办公室。
2. 2. The children were playing on the stairs when the fire alarm went off.
   孩子们在楼梯上玩耍时，火警铃响了。
3. 3. The elderly couple was using a walker to help them climb the stairs.
   这对老年夫妇正在使用助行器帮助他们爬上楼梯。