So they are very worried about H5N1, because - like the 1918 event - it seems to be evolving to become more deadly to mammals.是什么意思_So they are very worried about H5N1, because - like the 1918 event - it seems to be evolving to become more deadly to mammals.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句