1. A parallelogram with 4 congruent sides.
A parallelogram with 4 right angles.
A parallelogram with 4 congruent sides AND 4 right angles.

2. sides
right angles
rhombus rectangle

3. sides
congruent
always
square
square
squares
sometimes

4. sides
right angle
square
rhombus

5. Yes, CD ≅ DE since all sides of a square must be congruent.
The only quadrilateral that can have 4 congruent sides AND 4 congruent angles is a square.

6. perpendicular
AC BD
BCD DAB
ADC CBA
congruent
AC BD

7. parallelogram
sides
parallel congruent
congruent
supplementary
bisect
perpendicular
opposite angles

8. What!?!?!?!?
parallelogram
right angles
congruent
congruent
rectangle

9. W X Y Z
WXYZ is a parallelogram with 4 right angles. The opposite sides will be congruent. Opposite angles are congruent and supplementary. The diagonals will bisect and be congruent to each other.
No, without congruent diagonals the frame would just be a parallelogram and not a rectangle.