2 sentences

1. 画家正在一块洁白的画布上构思新作品。

   huà​jiā zhèng​zài yī kuài jié​bái de huà​bù shàng gòu​sī xīn zuò​pǐn.

   The painter is conceptualizing a new work on a pure white canvas.

   Source: Dong Chinese Dictionary

2. 画家先用铅笔在画布上打底，然后再开始上色。

   huà​jiā xiān yòng qiān​bǐ zài huà​bù shàng dǎ​dǐ, rán​hòu zài kāi​shǐ shàng​shǎi.

   The painter sketches a base with a pencil on the canvas before starting to paint.

   Source: Dong Chinese Dictionary