Once when I went for a walk in Weiming Lake, I accidentally picked up a small box. The box was stuffed with letters and a USB flash drive. I grabbed various clues and uncovered the mystery bit by bit, but the result made me feel sad. For us, every person we have ever interacted with in our lives will leave traces in our years, whether sad, happy, plain, or profound. We can't say which one you want, or even evaluate which one is more important to us, because in the trajectory of time, we have no right to look back. The only thing we can do is to quietly forget it, or to keep it silently in our hearts.