假想用剖切面将物体切断，仅画出物体与剖切面接触部分的图形及材料符号，这样的图形称为断面图。
A cross section of an object is a plane figure contained in the cutting plane and is produced when the object is imaginarily cut by that cut plane. It shows lony what is in the cutting plane.
A、正确
B、错误