Giving shadows a 3-d feel, or adding a single colour, will help separate them from the rest of the sketch.

加上3 - D的阴影效果，或者增加单独的颜色，将有助于和草图上的其他部分区分。

youdao

Thanks for the sketch. Are you using colour ink to draw?

谢谢您的素描。您是用彩色墨水来画的吗？

youdao

Learning colour is pen paint from life later; Should be pencil sketch next.

学完色彩以后就是钢笔写生；接下来就应该是铅笔素描。

youdao