Ginkgo Leaf Bookmark

When Su Wan was sorting out Gu Chenzhou's old books, her fingertips were caught on a piece of cardboard. She pulled it out and saw that it was a yellowed ginkgo bookmark, with the edges rubbed until it became hairy. On the back, there was a line of small words written in pen: "Wanwan, when this ginkgo tree reaches ten rings, we will get married." The handwriting is thin and thin, which is Gu Chenzhou's style. Su Wan's hand holding the bookmark began to tremble, and the ginkgo leaves outside the window were falling. This year is the tenth year they have known each other, and it is also the third year since Gu Chenzhou left.