french curve

Drawing in hand with the standard French curve usually has drawing and reading errors.

利用标准性能曲线板手工绘制往往具有较大的作图和读数误差。

French Curve: French curves are difficult to use and not really essential, but they are helpful if you can develop the skills.

曲线板：曲线板比较难使用，且不是必备品。但如果你掌握了使用的必要技巧，它有助于你的工作。