cut your teeth从字面上看是“切掉牙齿”，实际上是指小的时候，新的牙齿慢慢长出来的状态。现在这个词组多被引申为“在某方面获得最开始的经验”，也就是从菜鸟变成“老司机”的过程。

【例句】
They had just graduated from school and were anxious to cut their teeth on their job.
他们刚从学校毕业，迫切地希望在第一份工作中跃跃欲试。

Rowe did much of the trimming, cutting his teeth as an editor on the film.
Rowe初次尝试做一个电影编辑师，他做了大量的剪辑工作。