∵$$a-b$$  $$=\sqrt{2}-1-\left( 2\sqrt{2}-\sqrt{6} \right)$$  $$=\sqrt{6}-\left( 1+\sqrt{2} \right)$$  $$\approx 2.449-2.414\textgreater0$$，  ∴$$a\textgreater b$$；  ∵$$a-c$$  $$=\sqrt{2}-1-\left( \sqrt{6}-2 \right)$$  $$=\sqrt{2}+1-\sqrt{6}$$  $$\approx 2.414-2.449\textless{}0$$，  ∴$$a\textless{}c$$；  于是$$b\textless{}a\textless{}c$$． 
已知$$a=\sqrt{2}-1$$，$$b=2\sqrt{2}-\sqrt{6}$$，$$c=\sqrt{6}-2$$，那么$$a$$，$$b$$，$$c$$的大小关系是．
[a] $$a\textless{}b\textless{}c$$ 
[b] $$a\textless{}c\textless{}b$$ 
[c] $$b\textless{}a\textless{}c$$ 
[d] $$b\textless{}c\textless{}a$$ 