As Covid-19 cases skyrocketed across Britain in late December, Stuart Guest spent his vacation poring over scientific reports about air cleaning and filtration systems.
원문출처 : https://www.cnn.com/2022/01/11/world/covid-omicron-schools-uk-europe-us-cmd-intl/index.html
원문출처 : https://www.cnn.com/2022/01/11/world/covid-omicron-schools-uk-europe-us-cmd-intl/index.html