adj.发黑的;
例句:
Labial color is darker, nigrescent reason?
嘴唇颜色比较暗, 发黑的原因?
Incinerate fertilizer volatilizes nigrescent meeting flying.
灰化肥挥发发黑会飞花.
How to often brush vi babble to return nigrescent ah?
经常刷牙牙怎么还发黑啊?