rung|rungs

梯子的最上面一级有点松动了。

The top ___rung of the ladder feels a bit loose.

梯子的最上面两级横档有点松动。

The top two ___rungs of the ladder feel a bit loose.

他在公司里已经爬到了中层管理的位置。

He has reached the middle management ___rung of the company.