Old books change their colors
本文作者： TEENS
The pages of old books look yellow or brown. TNS 随着时间流逝，为什么书页会变黄？ If you look at old newspapers and books, you’ll find that they are yellow or brown. But why does old paper turn these colors? |  |
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中报二十一世纪（北京）传媒科技有限公司版权所有，未经书面授权，禁止转载或建立镜像。 主办单位：中国日报社 Copyright by 21st Century English Education Media All Rights Reserved 版权所有 复制必究 网站信息网络传播视听节目许可证0108263 京ICP备2024066071号-1  京公网安备 11010502033664号
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