Instead the trend reversed direction 5,000 years ago and rose gradually back to almost 700 ppb just before the start of the industrial era.是什么意思_Instead the trend reversed direction 5,000 years ago and rose gradually back to almost 700 ppb just before the start of the industrial era.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句