Plotting multiple surfaces on the same 3Ddisplay



Hello,

I'm using function plot3d to display 3D parametric defined surfaces :

plot3d([u,v,sin(u)*cos(v)], [u,-%pi,%pi], [v,-%pi,%pi]);

This work fine. No problem. But I can't manage to plot several surface 
on the same display.
The response may be obvious but I can't find it anywhere.

Thanks for any help !