Then, the opposite sides are congruent.
An isosceles trapezium
sometimes
Parallel
The Opposite Sides Parallel and Congruent Theorem states that if a quadrilateral has a pair of opposite sides that are parallel and congruent, then the quadrilateral is a parallelogram.
Every quadrilateral has opposite sides, but I'm assuming you probably are asking about a trapezoid.
No. The congruent sides need not be parallel.
rhombus
This quadrilateral is a trapezoid. In a trapezoid, one pair of opposite sides is parallel, and one pair of opposite sides is congruent. The other two sides are not parallel or congruent.
It is a trapezoid which has 1 pair of opposite parallel sides of different lengths
A trapezium.
the answer is a trapezium.