with(plots):
For reading questions:
p1:=implicitplot3d(x=4*y^2+4*z^2, x=-1..20, y=-3..3, z=-3..3, style=patchnogrid,axes=boxed):
p2:=spacecurve([4*t^2,t, 0], t=-2.23..2.23, color=blue, thickness=3,axes=boxed):
p9:=spacecurve([4*t^2,0,t], t=-2.23.. 2.23, color=green, thickness=3):
p3:=spacecurve([5,t, sqrt((5-4*t^2)/4)], t=-3.. 3, color=red, thickness=3):
p4:=spacecurve([5,t, -sqrt((5-4*t^2)/4)], t=-3..3, color=red, thickness=3):
p5:=spacecurve([10,t, sqrt((10-4*t^2)/4)], t=-3..3, color=red, thickness=3):
p6:=spacecurve([10,t, -sqrt((10-4*t^2)/4)], t=-3..3, color=red, thickness=3):
p7:=spacecurve([15,t, sqrt((15-4*t^2)/4)], t=-3..3, color=red, thickness=3):
p8:=spacecurve([15,t, -sqrt((15-4*t^2)/4)], t=-3..3, color=red, thickness=3):
display(p2,p3,p4,p5,p6,p7,p8,p9);
display(p1,p2,p3,p4,p5,p6,p7,p8, p9);