Passengers write down their personal information and sign commitment letters as they pass a temperature checkpoint set up to help control the spread of COVID-19 via a courtesy passage at Beijing Daxing International Airport in Beijing, capital of China, Dec. 9, 2020. Beijing Daxing International Airport has introduced courtesy passages into its COVID-19 prevention and control mechanism. Elderly passengers, as well as passengers without smartphones, can easily pass the airport's temperature checkpoints by registering with the ground staff and signing a commitment letter, even they don't have access to health-tracking apps on a mobile phone. (Xinhua/Ju Huanzong)