| 1 | Learning plane geometry well is the foundation of learning solid geometry well. | |
| 2 | The straight line is one of the most fundamental geometrical elements in plane geometry. | |
| 3 | Countless straight lines can be perpendicular to a plane through a single point. | |
| 4 | Digital printing has been widely used in publishing, graphic design, advertising and other fields. | |
| 5 | Whether it's flat printing or 3D printing, the right printing materials and environment are needed. |