Sometimes I look out the window at the people walking back and forth, and feel a sense of loss quietly arise in my heart. With a heavy sigh, I walked back to the familiar classroom, where there were sounds of drawings on paper, and then I joined in. I kept thinking about the method to solve the problem, but I couldn't solve it after thinking a lot. I threw the problem aside in frustration, but as soon as I stopped, a paragraph of notes floated in my mind. Memories were intermittent at first, but then they came like a flood. I held my head tightly and tried hard not to think about the memories that made me heartache. But I couldn't control myself. After all, this was the memory I had with her from the past. It was so beautiful and unforgettable that I was intoxicated every time.