1 Maybe you thought that they were just happy. After all, you probably sing or whistle when you are happy.
However, they sing most of the time for a very different reason. 2 Some scientists believe that birds do sing some of the time just because they are happy.
Do you know what a “territory” is? A territory is an area that an animal, usually the male, claims(声称)as its own. 3 No other families of the same species are wele. Your yard and house are your territory where only your family and friends are wele. If a stranger should enter your territory and threaten you, you might shout. Probably this would be enough to frighten him away. If so, you have actually scared the stranger away without having to fight him. A bird does the same thing. But he expects an outsider almost any time, especially at nesting(筑巢)season. So he is screaming all the time, whether he can see an outsider or not. 4 .
Birds sing loudest in the spring when they are trying to attract a mate and warn others not to enter the territory of theirs. You can see that birds have a language all their own. 5 A．Only he and his family are wele there.B．Most of it has to do with attracting mates and setting up territories.C．Have you ever wondered why birds sing?D．Their singing is actually a warning to other birds to stay out of their territory.E. Have you ever wondered why birds sing?
F. Most of the language is widely used.
G. This screaming is what we call a bird’s song, and it is usually enough to keep an outsider away.E
网友回答
(答案→)E
解析：本文是对鸟儿鸣叫声的研究，主要是两个目的，一个是吸引异性，另外一个是现实主权。
【小题1】E 根据After all, you probably sing or whistle when you are happy.说明当我们开心的时候，我们可能也会唱歌，故前面应该是指唱歌有关的内容，故E项符合上下文。
【小题2】D 根据上句However, they sing most of the time for a very different reason.说明鸟儿的歌声有不同的原因，也许就是警告地方离开自己的领地，故D项正确。
【小题3】A 根据前句A territory is an area that an animal, usually the male, claims(声称)as its own领地就是他声称属于他自己的地盘。别人不允许进入，故A正确。
【小题4】G 根据上句he is screaming all the time, whether he can see an outsider or not他一直在尖叫，也许这就是我们所谓的鸟儿的歌声，实际上是为了警告别的同类离开。故G项正确。
【小题5】B 根据本段第一行说明鸟儿的鸣叫是与吸引异性有关，以及第三段中鸟儿的叫声是为了警告同类，显示主权。故B说法符合上下文。