Gleaming airplanes have been returning to the empty blue skies above 30,000 feet in recent months, opening up travel possibilities as they skim the clouds on their way towards unfiltered sunshine.
원문출처 : https://www.cnn.com/travel/article/aviation-environmental-impact-2021/index.html
원문출처 : https://www.cnn.com/travel/article/aviation-environmental-impact-2021/index.html