So an easy thing to do in planar geometry is I want to make a line segment.
在平面几何里比较容易的一件事，就是做一个线段。
With points you can make a line; with line, planes; with planes, solids.
用点画成线，用线画成平面，用平面画成立体。
With points you can make a line; with lines, planes; with planes, solids.
用点画成线，用线画成平面，用平面画成立体。
With points you can make a line; with lines, planes; with planes, solids.
用点画成线，用线画成平面，用平面画成立体。
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