var('y', 'z')
C = parametric_plot3d((cos(t), sin(t), 3 - cos(t) - sin(t)), (t, 0, 2*pi), color = 'black')
S1 = plot3d(3 - x - y, (x, -2, 2), (y, -2, 2), color = 'green', opacity = 0.5)
S2 = parametric_plot3d((cos(t), sin(t), z), (t, 0, 2*pi), (z, 0, 6), color = 'blue', opacity = 0.5)
show(C + S1 + S2)