已知F是双曲线 $\frac{x^2}{a^2}$ ﹣ $\frac{y^2}{b^2}$ =1（a＞0，b＞0）的右焦点，A，B分别为其左、右顶点．O为坐标原点，D为其上一点，DF⊥x轴．过点A的直线l与线段DF交于点E，与y轴交于点M，直线BE与y轴交于点N，若3|OM|=2|ON|，则双曲线的离心率为（   ）

随着人类改造自然能力的不断增强，人类对地球家园造成的破坏性影响也越来越严重，人们通过“地球日”“地球一小时”等活动唤醒公众的环保意识，是因为①环境的人为恶化有一个从逐渐量变到根本质变的演变过程 ②环境的人为恶化是一个不可逆的从量变到质变的发展过程 ③环境的改变是人类不断征服自然地从量变到质变的过程 ④环境的改变是人与自然和谐相处的从量变到质变的过程

近年来，党和政府采取一系列措施，努力确保人民群众共享经济繁荣成果。下列收入分配格局中，能体现这一方向的是（   ）

我国夏季气温最低值出现在青藏地区的原因是（   ）

       America is a mobile society. Friendships between Americans can be close and real, yet disappear soon. They don't feel hurt. If the same two people meet again, even years later, they pick up the friendship. This can be quite difficult for us Chinese to understand. Friendships between us develop more slowly but may become lifelong feelings, extending（延伸）deeply into both families.
      There is another difficult point for us to understand .Although Americans treat friends warmly in their personal everyday lives, they don't show their politeness to them if it requires a great deal of time. But in China, we are usually generous with our time. We, as hosts, will appear at an airport even in the middle of the night to meet a friend. We may take days off from our work to act as guides to our friends: It is opposite in America, Americans cannot manage the time to do a great deal with a visitor outside their daily plans. They will probably expect the visitors to get themselves from the airport to the hotels. And they expect the visitors will phone them from there. Once the visitors arrive at their homes, the welcome will be full, warm and real.
       For Americans, it is often considered more friendly to invite a friend to their homes than to restaurants, except for business matters. Americans are ready to receive us foreigners at their homes, share their holidays, and their home life. So accept their hospitality（好客）at home and enjoy your visit in America!