读图和材料，回答下列问题。

材料一2014年2月7日至23日，第22届冬奥会在俄罗斯黑海之滨的索契成功举行。索契独特的地理优势，使之成为世界纬度最高的亚热带气候区，是俄罗斯唯一具有亚热带风情的旅游度假胜地，被称为俄罗斯的夏日之都。

材料二 索契和温哥华（第21届冬奥会主办城市）所在地区局部图

周末的时光，阅读是小明的最爱．

    碳元素既是组成生物体的基本元素，也是组成地壳中岩石和化石燃料的主要元素．在自然界中，有硬度极高的金刚石、最软的矿物之一石墨；有植物光合作用所依赖的二氧化碳，也有有毒气体一氧化碳；还有可用作建筑材料的大理石、生命的基石﹣﹣蛋白质等．

    植物的光合作用是利用水和空气中的二氧化碳，生成葡萄糖并释放出氧气；而动植物的呼吸过程和化石燃料的燃烧则消耗氧气，放出二氧化碳；从而完成了二氧化碳在自然界的循环．

    1828年，德国化学家维勒用无机化合物氰酸铵（NH₄CNO）合成出有机化合物﹣﹣尿素CO（NH₂）₂，由此突破了无机化合物与有机化合物之间的界限．继维勒之后，人们以含碳无机化合物为原料，相继合成出大量的有机化合物，满足了人类在能源和材料等方面的需要．

    总之，碳及其化合物间的转化有单质与氧化物、氧化物与酸、氧化物与氧化物、以及无机物与有机物之间的转化等．

阅读中请我们思考：

在场强E=1.0×10²V/m的匀强电场中，有相距d=2.0×10^﹣2m的a、b两点，则a、b两点间的电势差可能为（   ）

下列计算：
　 ①3a＋2b＝5ab； ②5y²—2y²＝3； ③7a＋a＝7a²； ④4x²y－2xy²＝2xy．
其中正确的有(  )

   A lift is wonderful. It is really only a small room. Rooms usually stay in one place. Lifts travel up and down all day long.
    Sometimes a worker stands in the lift. He or she operates it up and down. In modern lifts there is no worker.  People walk in. They know which floor they want. They push a button and the lift goes to that floor. It is all very fast and easy.
   Lifts are very important to us. Why? Think about a tall building. Maybe it has twenty floors. Maybe it has fifty or more. Who can walk up all the stairs? Maybe people can climb them one time. Can someone climb thirty floors to an office every day? Can small children walk up to their room on the twenty-fourth floor? Can their mothers and fathers carry food up all those stairs? Of course not.
   We can have high buildings because we have lifts. We could not have all the beautiful tall buildings in the world without lifts. They are really wonderful.