第一部分： 阅读理解（共两节，满分40分）
第一节（共15小题；每小题2分，满分30分）
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。
A
In the United States, 30 percent of the adult population has a weight problem. To many people, the cause is obvious: we eat too much. But scientific evidence does little to support this idea. Going back to the America of 1910, we find that people were leaner than today, yet they ate more food. In those days people worked hard physically, walked more, used machines much less, and didn’t watch television.
