单词：rungs
n. 梯级（rung的复数形式）
n a crosspiece between the legs of a chair
n one of the crosspieces that form the steps of a ladder
n one of the crosspieces that form the steps of a ladder
rungs的用法和样例：
例句
- Dots on the three lowest rungs would indicate that the system possesses no internal energy.圆点在三个最低梯级上，就表示这个系统没有内能。
- Just use the rungs and sides of the ladder as support for the vines.Let the pumpkins grow on the steps for further support.就用梯级或梯子的侧面作为藤蔓的支撑物，让南瓜在梯级上生长，获得支撑。