A rectangle is a parallelogram whose interior angles are right angles.
A common property of parallelograms is that they have two pairs of parallel sides and two pairs of sides of equal lengths.
Therefore, the correct answers are
2 pairs of parallel sides.
2 pairs of sides with equal lengths.
An equilateral triangle is a triangle with sides having equal length
Equilateral and Iscosceles triangles have 2 sides of equal length.