懵懂已是往事
[mĕng dŏng yĭ shì wăng shì]
'Naivete has Become the Past' symbolizes that youthful naivety and purity have already faded into memories, expressing some nostalgia for innocence or a simpler time in one's life, as they may have grown more mature and experienced over time. People might pick this username because they have undergone great changes or growth in their lives, leaving behind their innocent and naive youth.