Final answer:
In a parallelogram, the opposite sides are always parallel. Another polygon where all the opposite sides are also always parallel is a trapezoid. Additionally, a rhombus is another correct answer.
Step-by-step explanation:
In a parallelogram, the opposite sides are always parallel. One other polygon where all the opposite sides are also always parallel is a trapezoid. In a trapezoid, one pair of opposite sides are parallel, while the other pair are not. However, it is important to note that rhombus is also a correct answer. In a rhombus, all four sides are equal in length and opposite sides are parallel.