题目

       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.       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（物种）are welcome .Your yard and house are 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 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 .This screaming is what we call a bird’s song ,and it is usually enough to keep an outsider away.       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 .Most of it has to do with attracting mates and setting up territories.56．Some scientists believe that most of the time birds’ singing is actually       .       A．an expression of happiness                   B．a way of warning       C．an expression of anger                         D．a way of greeting57．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 .58．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.56．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. 答案：56.B   解析：见文章第二段中的Their singing is actually a warning to other birds to stay out of their territory.它们的歌唱实际上是一种警告，让别的鸟离开他们的领地。而A是片面的观点。57.D  解析： 从文章第三段中的A territory is an area that an animal ,usually the male, claims as its own.可以知道它的含义，可以翻译为“领地”。58.B  解析：从文章第三段和第四段的意思，可以知道鸟儿在筑巢季节，发出声音主要是为了把外来者赶跑。59.A  解析：文章中大量的使用了人的活动。如：you probably sing or whistle when you are happy；Your yard and house are your territory；If so, you have actually scared the stranger away without having to fight him.我们就可以看出：作者用人的活动来与鸟儿的活动来做比较，这样在讲道理的时候，就明白易懂。据此就可以知道作者所用的说明法为：比较法。

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