"我最难忘"可以用英语表示为"the thing that I will never forget"或"the thing that sticks in my mind the most". 这个表达来自英语中常用的俗语"to stick in one's mind", 意思是某件事情牢牢地印在某人的记忆中, 并且很难忘记. 下面是一些例句:

The thing that I will never forget is the day I met my wife. (我永远都不会忘记我遇见我妻子的那一天.)
The thing that sticks in my mind the most about my trip to Paris is visiting the Eiffel Tower. (我去巴黎旅行最难忘的事情就是参观埃菲尔铁塔.)