阅读理解。

    This is asong millions of Americans will hear this New Year's Eve. It is called Auld Lang Syne（《友谊天长地久》）. It is the traditional music played during the New Year's celebration. Auld Lang Syne is an old Scottish poem.It tells about the need to remember old friends.

The words "auld langsyne "mean" old long since". No one knows who wrote the poemfirst. However, a version by Scottish poet Robert Bums was published (出版) in 1796. The words and music we know today first appeared in a songbookthree years later.

    The songis played in the United States mainly on New Year's Eve. The version (译文) you are hearing today is by the Washington Saxophone Quartet.

    As we endour program with Auld Lang Syne. I would like to wish all of our radio friendsa very Happy New Year! This is Buddy Thomas.

（Ⅰ）求抛物线C₁的方程；

（Ⅱ）已知椭圆C₂： $\frac{x^2}{m^2}+\frac{y^2}{n^2}$ =1（m＞n＞0）的一个焦点与抛物线C₁的焦点重合，且离心率为 $\frac{1}{2}$ ．直线l：y=kx﹣4交椭圆C₂于A、B两个不同的点，若原点O在以线段AB为直径的圆的外部，求k的取值范围．

如图，矩形ABCD的周长为20cm，两条对角线相交于O点，过点O作AC的垂线EF，分别交AD，BC于E，F点，连接CE，则△CDE的周长为（　　）

“万物的存在与否，全在于人的感觉。一阵风吹过，有人觉得冷，有人觉得凉爽。难受与惬意，全在于人的感觉。”提出上述观点的哲学家是