In Banff National Park in Canada, scientists have documented changes brought by wolves that returned on their own in the1980 s: willows reappeared, the diversity and abundance of songbirds doubled.是什么意思_In Banff National Park in Canada, scientists have documented changes brought by wolves that returned on their own in the1980 s: willows reappeared, the diversity and abundance of songbirds doubled.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句