阶梯这个词用英语怎么说?就是这句话里面:书是人类进步的阶梯.这里的阶梯怎么翻译好?

阶梯 ladder
书是人类进步的阶梯Books are the ladders for us to climb high.
stairs:n.楼梯
书是人类进步的阶梯Books are the mankind's progressive stairs.
ladder:[ 'lædə ]
n.梯子
例句与用法:
1.Hard work is often a ladder to success.
发奋工作常是通向成功的阶梯.
2.The ladder has eight rungs.
这梯子有八级.
stairs
例句与用法:
1.The old woman fell down a flight of stairs.
那位老太太从一段楼梯上摔了下来.
2.Could you help me up the stairs?
你能扶我上楼梯吗?
3.Your heart beat will quicken when you run up the stairs.
跑上楼梯时,心跳会加速.
4.They rushed up the stairs.
他们冲到楼上.
5.He ran down the stairs.
他跑下楼梯.

ladder

ladder
path is good too in this context

staircase

step

stair(s)