Recently, the epidemic broke out in Chaoyang District, Beijing, showing the characteristics of concealed transmission and rapid development. In order to effectively block the spread of the epidemic, Chaoyang District, Beijing has expanded the scope of nucleic acid detection. From April 25, people living and working in Chaoyang District will be tested for nucleic acid once a day on April 25, 27 and 29. (on April 25, at a nucleic acid sampling point in Balizhuang street, Chaoyang District, Beijing, the staff registered the information for the citizens who came for nucleic acid testing.) (on April 25, citizens were taking nucleic acid samples at a nucleic acid sampling point in Balizhuang street, Chaoyang District, Beijing.) (on April 25, at a nucleic acid sampling point in Balizhuang street, Chaoyang District, Beijing, the staff registered the information for the citizens who came for nucleic acid testing.) (on April 25, citizens were taking nucleic acid samples at a nucleic acid sampling point in Balizhuang street, Chaoyang District, Beijing.) (on April 25, at a nucleic acid sampling point in Balizhuang street, Chaoyang District, Beijing, citizens were waiting in line for nucleic acid sampling.) (on April 25, at a nucleic acid sampling point in Balizhuang street, Chaoyang District, Beijing, citizens lined up to scan the code for nucleic acid sampling.) (Xinhua News Agency)