What are the missing reasons in the proof?

Given: Parallelogram ABCD with diagonal segment BD
Prove: Triangle ABD is congruent to triangle CDB

Statements: Reason
1. Segment AD is parallel to segment BC: Definition of a parallelogram
2. Angle ADB is congruent to angle CBD: Alternate Interior Angles Theorem
3. Segment AB is parallel to segment CD:?
4. Angle ABD is congruent to angle CDB:?
5. Segment DB is congruent to segment DB:?
6. Triangle ABD is congruent to Triangle CBD:?

1 answer

3. Segment AD is congruent to segment BC: Opposite sides of a parallelogram are congruent
4. Opposite sides of a parallelogram are parallel
5. Reflexive property of congruence
6. Side-Angle-Side (SAS) congruence theorem