Marks caused by mask are seen on the face of a medical worker at Fuzhou Pulmonary Hospital of Fujian in Fuzhou, southeast China's Fujian Province, Jan. 31, 2020. (Photo by Wang Yi/Xinhua)

Pro-Brexit supporters celebrate Brexit at a gathering at Parliament Square, in London, Britain, on Jan. 31, 2020. (Photo by Stephen Chung/Xinhua)

Staff members disinfect the cabin of an airplane after its arrival at the Haikou Meilan International Airport in Haikou, south China's Hainan Province, Jan. 31, 2020. (Photo by Pu Xiaoxu/Xinhua)

A child wearing mask waits for a train at Zhengzhou East Railway Station in Zhengzhou, central China's Henan Province, Feb. 1, 2020. (Xinhua/Li An)

Workers work at the construction site of Huoshenshan (Fire God Mountain) Hospital in Wuhan, central China's Hubei Province, Feb. 1, 2020. (Xinhua/Xiao Yijiu)

Doctors, separated by the window of an isolation ward, discuss treatment options with intercoms at Fuzhou Pulmonary Hospital of Fujian in Fuzhou, southeast China's Fujian Province, Jan. 31, 2020. (Photo by Wang Yi/Xinhua)

A medical worker treats a patient at an isolation ward in a hospital in southwest China's Chongqing, Feb. 1, 2020. (Xinhua/Wang Quanchao)

Sofia Kenin of the United States returns the ball during the women's singles final against Garbine Muguruza of Spain at the Australian Open tennis tournament in Melbourne, Australia on Feb. 1, 2020. (Photo by Bai Xue/Xinhua)

Staff members receive takeaways from a deliveryman at a hospital in Wuhan, central China's Hubei Province, Jan. 31, 2020. In the middle of a severe epidemic, Wuhan in central China's Hubei Province lost the hustle and bustle of the past, with few cars and pedestrians on the roads. For the people staying at home to avoid the infection of novel coronavirus, the takeaway deliverymen in the city have become the bridge between them and the outside world. (Xinhua/Li He)

This combo photo shows before (Top) and after the flag of the European Union (EU) being lowered down on the building of the British Embassy and UK Representation to the EU Brussels, in Brussels, Belgium, Jan. 31, 2020. (Xinhua/Zheng Huansong)

People attend the opening ceremony of Myanmar Ethnics Culture Festival in Yangon, Myanmar, Feb. 1, 2020. (Xinhua/U Aung)

Photo taken on Jan. 31, 2020 shows a bushfire in the Orroral Valley, south of Canberra, Australia. (Photo by Liu Changchang/Xinhua)

Sofia Kenin of the United States kisses the trophy during the awarding ceremony after the women's singles final against Garbine Muguruza of Spain at the Australian Open tennis tournament in Melbourne, Australia on Feb. 1, 2020. (Photo by Bai Xue/Xinhua)