Which season is your favourite season, spring, summer, autumn or winter? I like autumn best. Autumn is the time for harvest(收获). In autumn I can eat many different fruits：apples, pears, grapes and so on. I can also eat fresh vegetables. Autumn is cool. I feel comfortable(舒适的). I am happy to see the leaves turn red and yellow.

① $\sqrt{2}$ ﹣1与2﹣ $\sqrt{3}$ ；②2﹣ $\sqrt{3}$ 与 $\sqrt{6}$ ﹣ $\sqrt{5}$ ；

（Ⅱ）类比以上结论，写出一个更具一般意义的结论，并给出证明．

函数f（x）= $\frac{\sqrt{x+4}}{e^x-1}$ 的定义域为____．

下列叙述不能证明海陆变迁的是(  )