单词nigrescence
n.: 变黑；(颜色；皮肤；眼睛等的)发黑
网络: 表面发黑；黑化
变黑;(颜色;皮肤;眼睛等的)发黑
But the sky sudden nigrescence , has combined at least 30 minutes rain storms.
但天空突然变黑了，并下了至少30分钟的暴雨。
First, strengthens against exposes to the sun, against exposes to the sun can complete can prevent the cheek nigrescence .
第一、加强防晒，防晒做得好就能预防脸蛋变黑。
People can feel nigrescence but it"s not obvious.
能感到变黑的感觉，但不是很明显。
Because smokes can cause the skin cell to be at the anoxic condition, thus causes the eye socket nigrescence ;
因为吸烟会使皮肤细胞处于缺氧状态，从而使眼圈变黑；
The cause of color and luster nigrescence about cooking with soy sauce
酱油烧菜色泽发黑原因剖析
Excellent thermal stability, no nigrescence under the high temperature to ensure good surface finish;
热稳定性能优异，在高温下不发黑发黄，保证铸件的表面光洁度；
Study on the technique of steel normal-temperature quick nigrescence
钢铁常温快速发黑技术的研究
Study on Nigrescence Technics for Axes Shelves
轴档发黑工艺的研究