1. rectangle: 1 4 5 7 9

Triangle: 2 6

Square: 4 9

Quadrilateral: 1 3 4 5 7 8 9

2 the opposite sides are equal: B C D

Four sides are equal: c

Note: 1 square is a special rectangle.

Square, rectangle and parallelogram are special quadrangles.

The opposite sides of a square, a rectangle and a parallelogram are equal respectively.