I went to Fuxing this afternoon, and saw a lot of teachers and schoolmates. I never felt so happy in this school before. Even the view of Wu Yan's back made me happy, not only for his image in my memory, but also for a long period of good time that he stayed with us. My talking with Mrs. Gu seemed to be the most surprising present for me today, although tommorrow is the National Teachers's Day and I should be the one who gives presents to my teachers(obviously I didn't prepare any present today...orz). It's hard for me to retell what she told me today, but I memorized the most valuable sentence I thought deeply. "The most important thing isn't the distance between x1 and xn, but the delta." she said. I really think I should go to Fuxing more frequently.