Geometry

Question Analysis：
Tests understanding of how many congruent opposite sides are needed to prove a parallelogram.

Key Concept Explanation:
Only one pair of congruent opposite sides is not enough. Both pairs are required.

Step-by-Step Solution：
One pair congruent ≠ sufficient
You need either both pairs congruent, or the pair must be both congruent and parallel

Common Mistakes：
B...