sketch clock

例句：

1. 1.The artist drew a rough sketch of the building before starting to paint it.
   艺术家在开始绘画之前画了一幅建筑的粗略草图。
2. 2. The engineer made a sketch of the new bridge design before presenting it to the client.
   工程师在向客户展示新桥梁设计之前画了一张草图。
3. 3.The scientist used a diagram to explain the chemical reaction in the experiment.
   科学家用示意图来解释实验中的化学反应。