They were used to outline figures to show boundaries just like you might use solid lines in a pencildrawing.
它们被用来勾勒图形以显示边界，就像你在铅笔画中使用实线一样。
2
Let us constantly with a pencildrawing, painting non-stop to make vivid movies.
让我们用铅笔不停地画、不停的画、做出生动的电影吧。
3
A vector drawing is like a pencildrawing where you take a pencil from one point to another and connect the points with straight lines, curved lines, rectangles, and ellipses.