The view of symmetrical part can be drawn a half or quarter part, and two continuous thin lines paralleling to each other should be drawn on the two ends of the perpendicular center line, as shown in Fig.12.

• 当机件上具有相同的结构要素（如孔、槽）并按一定规律分布时，只需要画出几个完整的结构，其余的可用细实线连接或画出他们的中心位置，并在图中注明其总数，如图12所示。