plotting - Normal lines to surfaces or planes in a 3D plot

How do I make the normal line to a plane actually look perpendicular?

cc = Plot3D[2 x + y, {x, -2, 2}, {y, -2, 2}, PlotRange -> {-4, 4}]

bb = ParametricPlot3D[{2 t, t, -t}, {t, -1, 1}, PlotStyle -> Thick]

Show[cc, bb]

The line doesn't look even close to perpendicular to the plane.