求问这个句子中的once的意思

Question

Although contradictory to his once childish nature, he's learned to survey his targets before attacking and killing them.

Answer 1

contradictory ,相反的
once 是曾经、一度的意思
he has learned 就是表示现在的动作了
跟他一度/曾经孩子气/幼稚的本性相反，他现在已经学会在攻击杀害他的猎物/目标之前进行调查。

Answer 2

曾经