在每一次实验里，研究人员对文雀们播放同一首歌直到它们熟悉这首歌的调子，然后把歌的音符打乱编成一些新歌。
In each experiment, the birds were presented with the same songs until they became familiarized with the tune. The researchers then created novel songs by shuffling the notes around.
就如谚语所说煤矿里的金丝雀一样，近10,000种已知的鸟类在自然界中扮演着“晴雨表”的角色，它们的数量可以用来评价其栖息地的健康情况。
Like the proverbial canary in a coal mine, the nearly 10, 000 known bird species act as "environmental barometers" whose populations can appraise the greater well-being of their habitats.
煤矿里不再有金丝雀了，这是有原因的。
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