You get nothing, either it will always be a parallelogram, or one pair of sides is parallel and the other sides are arbitrary. You must understand that the plane you are talking about is a plane figure with infinite extension and narrow sense. You want to describe a narrow plane, so it depends on what shape your parallel plane is. The estimate for that cross section is infinite. Then it is estimated that the other plane you are talking about is limited, and it is a positive plane with parallel opposite sides. Then the conclusion becomes a parallelogram section, unless you want to expose two angles between two planes, hehe. As long as the angle is not between two faces, it is a parallelogram. If the interface is infinite, helpless and nothing can be cut out, it is an infinite surface between two parallel lines.