\frac{\sqrt{3}+\sqrt{5}}{3-\sqrt{6}-\sqrt{10}+\sqrt{15}}= .
\sqrt{3}-\sqrt{2}
\sqrt{3}+\sqrt{2}
\sqrt{2}-\sqrt{3}
\sqrt{5}+\sqrt{2}
\sqrt{5}-\sqrt{2}
~~~~\frac{\sqrt{3}+\sqrt{5}}{3-\sqrt{6}-\sqrt{10}+\sqrt{15}}
=\frac{\sqrt{3}+\sqrt{5}}{\sqrt{3}(\sqrt{3}+\sqrt{5})-\sqrt{2}(\sqrt{3}+\sqrt{5})}
=\frac{\sqrt{3}+\sqrt{5}}{(\sqrt{3}+\sqrt{5})(\sqrt{3}-\sqrt{2})}
=\sqrt{3}+\sqrt{2}.
