teeth yellowing
paper yellowing
leaf yellowing
age-related yellowing
A: Have you noticed the yellowing of these documents?
A：你注意到这些文件的变黄现象了吗？
B: Yes, they have been kept in a damp room.
B：是的，它们一直被存放在潮湿的房间里。
1) 颜色变黄的过程
2) 植物叶片变黄
3) 牙齿或物品发黄
1. 变黄；变黄现象
noun
1. The process of becoming yellow.