已知椭圆E： $\frac{x^2}{a^2}+\frac{y^2}{b^2}$ =1（a＞b＞0）的两个焦点与短轴的一个端点是直角三角形的3个顶点，直线l：y=﹣x+3与椭圆E有且只有一个公共点T．

①北京所在经线的地方时  ②120°E经线的地方时

③北京所在的东八区的地方时  ④北京所在的东八区的区时

    I' m David, a baby penguin (企鹅). It is snowing outside. I am staying____my nest (~) and waiting for my parents. They went out yesterday to ____food for me. I feel so cold and hungry now because we don't have any food at all. In the last few years,____developed the economy (发展经济), but they forgot the____

    They cut many trees down and ____ lots of factories. The____ from those factories soon changed the climate (改变气候). So it's harder for my parents to find food. What's worse,____ penguins died because of the climate change. But now, people in the world seem to know their mistakes (错误) and begin to do something to save the world. I think we can live a better life in the____

以直角坐标系xOy的原点为极点，x轴的非负半轴为极轴，且两坐标系取相同的长度单位．已知曲线C₁的参数方程为： $\{\begin{array}{c}x=2cos\theta \\ y=2sin\theta \end{array}$ （θ为参数），将曲线C₁上每一点的纵坐标变为原来的 $\frac{1}{2}$ 倍（横坐标不变），得到曲线C₂，直线l的极坐标方程： $\sqrt{3}\rho cos\theta +2\rho sin\theta +m=0$ ．

（Ⅰ）求曲线C₂的参数方程；

（Ⅱ）若曲线C₂上的点到直线l的最大距离为 $2\sqrt{7}$ ，求m的值．