踏脚石

例句：

1. 1. The old man used to climb the mountain with his grandson as a stepping stone.
   这位老人过去常常带着孙子作为踏脚石攀登这座山。
2. 2. The company's success is built on the foundation of many stepping stones.
   公司的成功建立在许多踏脚石之上。
3. 3. He was a stepping stone for the young lawyer who would become his boss.
   他成为了那位年轻律师的踏脚石，后者后来成为他的老板。