When the parabola passes through the point (0,-1), the parabola and the rectangle have three intersections. If the point (0,-1) is substituted, it is 1-k=- 1, and the solution is k=2.

When the parabola continues to translate downward, the parabola and sentence pattern have four intersections. When passing through point C and point D, there are only two intersections between parabola and rectangle. Substitute it into point D(2,-1).

4+ 1-k=- 1, and the solution is k=6.

So the value range of k is 2.