Passengers wait for a train to depart from the Hankou Railway Station in Wuhan, central China's Hubei province, Friday January 13, 2017. Officials expect that Chinese travelers will make almost 3 billion trips during the holiday travel rush that starts runs through Feb. 21. These trips include intercity flights, trains and local bus rides to villages for China's 1.4 billion people. (Photo by Chinatopix via AP Photo)

A U.S. Navy F18 fighter jet takes off from aircraft carrier USS Carl Vinson during a FONOPS (Freedom of Navigation Operation Patrol) in South China Sea, March 3, 2017. The U.S. military took journalists Friday to the carrier on routine patrol off the disputed South China Sea, sending a signal to China and American allies of its resolve to ensure freedom of navigation and overflight in one of the world's security hotspots. (Photo by Erik De Castro/Reuters)

This photo taken on October 8, 2017 shows dancers posing in formation to celebrate the upcoming Party Congress, in Rongan in China' s southern Guangxi region. China will convene its 19 th Party Congress on October 18, state media said, a key meeting held every five years where President Xi Jinping is expected to receive a second term as the ruling Communist Party' s top leader. (Photo by AFP Photo/Stringer)

Yang Juan, an employee at Goopal Group, takes a nap in her seat after lunch, in Beijing, China, April 21, 2016. Office workers sleeping on the job is a common sight in China, where a surplus of cheap labour can lead to downtime at work. But in China's technology sector, where business is growing faster than many start-up firms can hire new staff, workers burn the midnight oil to meet deadlines and compete with their rivals. Some companies provide sleeping areas and beds for workers to rest during late nights. (Photo by Jason Lee/Reuters)

A child plays with a mock submachine gun at a model Mass Transit Railway (MTR) station to mark the National Security Education Day at Hong Kong Police College in Hong Kong, China on April 15, 2021. The “education day” was organized to promote the sweeping legislation China imposed last year, marked with school activities, games and shows, and a parade by police and other services. (Photo by Tyrone Siu/Reuters)

A visitor views a human body specimen during the “Human Body's Wonder Scientific Travelling Exhibition” at the Haikou Gymnasium April 30, 2006 in Haikou of Hainan Province, China. The exhibition displays 13 complete real human body specimens and about 300 pieces of small samples, such as organs, skin, etc with the purpose to promote science and help people know more about their bodies. (Photo by China Photos/Getty Images)

Sea of clouds is seen after a rainfall at the Huangshan Mountain scenic spot on April 10, 2019 in Huangshan, Anhui Province of China. (Photo by Fang Lihua/Qianlong.com/VCG via Getty Images)

A villager harvests water chestnuts in Feijiadai Village, Zhejiang Province, China on September 20, 2019. (Photo by Huang Zongzhi/Xinhua News Agency/Barcroft Media)