第一部分：听力（略）
第二部分 阅读理解（共两节，满分60分）
第一节（共15 小题；每小题3分，满分45分）
A
Have you ever wondered why birds sing? Maybe you thought that they were just happy．After all，you probably sing or whistle when you are happy．
Some scientists believe that birds do sing some of the time just because they are happy．However，they sing most of the time for a very different reason．Their singing is actually a warning to other birds to stay out of their territory.
