russeting

例句：

1. 1. The old apple tree has a rusty bark that looks like it's been there for centuries.
   那棵老苹果树的树皮已经发黑，看起来像是经历了几个世纪。
2. 2.The paint on the walls is fading, and we need to repaint them before they completely disappear.
   墙上的油漆正在褪色，我们需要在它们完全消失之前重新粉刷。
3. 3.The sun had already set, and the sky was turning from blue to russet as the evening approached.
   太阳已经落山了，天空从蓝色变成了黄昏时的棕褐色。