One morning Mr. Green is driving 1the country and2a small bookshop. When he sees an old man3the side of the road, he stops his car and says to the old man, "I want 4to the Sun Bookshop. Do you know it?" "Yes, "the old man answers, "I 5 you the way. "He6Mr. Green's car, and they drive about twelve miles.7they come to a small house, the old man says, "Stop here. "Mr. Green stops and 8the house. "But this isn't a bookshop, "he says to the old man. "Right, "the old man answers, "This is my house. And I'll show you the way 9the bookshop. Turn around and go back nine miles10you'll see the bookshop. "

已知双曲线$\frac{x^2}{a^2}-\frac{y^2}{b^2}=1\left(a>0,b>0\right)$的右焦点为F(2，0)，设A，B为双曲线上关于原点对称的两点，AF的中点为M，BF的中点为N，若原点O在以线段MN为直径的圆上，直线AB的斜率为$\frac{3\sqrt{7}}{7}$，则双曲线的离心率为（    ）

我国政府下令停止开垦三江平原上的沼泽地，主要原因是

沙柳是防风固沙的优良树种。但是由于种植沙柳费钱费力，又无法带来经济效益，人们不愿意种植。针对这种情况，宁夏自治区某地政府支持建立了以沙柳为原料的制板、造纸加工企业，带来了明显的经济效益，极大地调动了个人和集体的积极性。大家争相承包荒地，种植沙柳蔚然成风。从哲学上看，种植沙柳防风固沙从难以实施到有效实施，其成功之处在于（    ）