Have you ever wondered why birds sing? Maybe you thought that they were just happy. After all, you probably sing 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.
Do you know what a “territory” is? A territory is an area that an animal, usually the male, claims (声称) as its own. Only he and his family are welcome there. No other families of the same species are welcome. Your house is your territory where only your family and friends are welcome. 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 frightened 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. This screaming is what we call a bird’s song, and it is usually enough to keep an outsider away.
小题1:Some scientists believe that most of the time bird’s singing is actually ________.
A．an expression of happiness
B． a way of warning
C．an expression of anger
D． a way of greeting小题2:What is a bird’s “territory”?
A．A place where families of other species are not accepted.
B．A place where a bird may shout at the top of its voice.
C．An area for which birds fight against each other.
D．An area which a bird considers to be its own.小题3:Why do birds keep on singing at nesting season?
A．Because they want to invite more friends.
B．Because their singing helps frighten outsiders away.
C．Because they want to find outsiders around.
D．Because their singing helps get rid of their fears.小题4:How does the writer explain birds’ singing?
A．By comparing birds with human beings.
B．By reporting experiment results.
C．By describing birds’ daily life.
D．By telling a bird’s story.小题5:What does the underline word “screaming” in paragraph 4 mean?
A．哭喊声
B．令人惊愕的
C．尖叫声
D．尖叫的
小题1:B
小题2:D
小题3:B
小题4:A
小题5:C
题目分析：文章讲述了鸟儿的叫声并非全都是在唱歌，而是一种发出的警告，警示同伴或是吓退入侵者。
小题1:细节题。从Their singing is actually a warning to other birds to stay out of their territory.可知，绝大多数时间鸟儿唱歌是为了警告同伴远离危险，故选B
小题2:细节题。从A territory is an area that an animal, usually the male, claims (声称) as its own.可知territory是指鸟儿认为是自己的领地的地方，故选D
小题3:细节推断题。从you have actually frightened 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.可知它在筑巢期叫的原因是帮助吓退入侵者，故选B
小题4:细节题。文章很多地方都拿人与鸟儿进行比较，如If so, you have actually frightened the stranger away without having to fight him.可知选A
小题5:推断题。上文讲到鸟儿这种叫声是为了吓退入侵者，故应该是尖叫声的意思，故选C
点评：科普环保类说明文的作答往往围绕所叙述的一种物质来展开全文，对于此类文短题多的文章必须对每句话的内容进行仔细的理解，细节题的考察占到了大部分的比例，所以学生需要结合题目中的关键字迅速定位来找到正确的答案。