Axiom 2: Axiom of Line Segment: The line segment between two points is the shortest.
Axiom 3: Parallel Axiom: Only one straight line is parallel to a point outside the straight line.
Axiom 4-6: the axiom of judging parallel lines: the internal angles are equal and the two straight lines are parallel; The same angle is equal, and two straight lines are parallel; Two straight lines complementary to the inner corner of the side face are parallel.
Axiom 7-9: Axiom for judging triangle congruence: SASSSS Asa.