For instance, traumatic hind if the skin is built-in dust, coal ash sundry, if clean ungodliness, colored grain remain can form ugly dust coloring inside the skin.

• 比如，外伤后如果皮肤嵌入粉尘、煤灰等杂物，如果清洗不净，有颜色的颗粒残留在皮肤内就会形成难看的粉尘染色。