Opposite sides of a parallelogram are equal. In length this attribute of a parallelogram is blank true of a quadrilateral and blank true of a rectangle.
The attribute of opposite sides being equal is always true for a parallelogram and it is sometimes true for a quadrilateral. On the other hand, for a rectangle, this attribute is always true as well, since a rectangle is a special case of a parallelogram where all angles are right angles.
