A number of prominent economists have also argued that it's harder for the poor to climb the economic ladder today because the rungs(横档) in that ladder have grown farther apart.
出自-2015年12月阅读原文
柯林斯高阶英汉双解学习词典释义
Rung is the past participle of ring .
N-COUNT
梯级;横档
The rungs on a ladder are the wooden or metal bars that form the steps.