At this time, scientists cannot be certain exactly when the next pandemic will occur, and whether it will rival the experience of the 1918-19 pandemic or be more muted like in 1957-58 and 1968-69.是什么意思_At this time, scientists cannot be certain exactly when the next pandemic will occur, and whether it will rival the experience of the 1918-19 pandemic or be more muted like in 1957-58 and 1968-69.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句