1. There are two kinds of positional relationships between two straight lines in the same plane: intersecting and parallel, and verticality is a special case of intersection.

2. On the same plane, two disjoint straight lines are called parallel lines. If two straight lines have only one common point, they are said to intersect; If two straight lines have no common point, they are said to be parallel.

5. Definition of the number axis: specify the origin, the straight line with unit length in the positive direction is called the number axis, and the three elements of the number axis are indispensable.

4. Translation: In a plane, a figure moves a certain distance in a certain direction. This movement of graphics is called translation transformation, or translation for short.

5. Definition of the number axis: specify the origin, the straight line with unit length in the positive direction is called the number axis, and the three elements of the number axis are indispensable.