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鸟儿为什么要歌唱春天,雄鸟尽情地歌唱不止,一是为了吸引雌鸟;二是向外界宣布,这里是它的势力范围,不可侵
Why birds sing spring, the male enjoy singing more than one, in order to attract the female; the second is announced to the outside world, here is its sphere of influence, inviolable