怎样用mathematica软件将两个三维图形和在一起?

用 Show
a = Plot3D[Sin[x + y],{x,-2,2},{y,-2,2}];
b = ContourPlot3D[
x^2 + y^2 - z^2 == 0,{x,-2,2},{y,-2,2},{z,-2,2}];
Show[a,b]