A teacher conducts disinfection at a kindergarten in Weiyang District of Xi'an, northwest China's Shaanxi Province, June 8, 2020. Xi'an has reopened kindergartens with opening qualifications since Monday under voluntary returning principle. (Xinhua/Zhang Bowen)

Children read books at a classroom of a kindergarten in Weiyang District of Xi'an, northwest China's Shaanxi Province, June 8, 2020. Xi'an has reopened kindergartens with opening qualifications since Monday under voluntary returning principle. (Xinhua/Zhang Bowen)

A child hugs a teacher after arriving at a kindergarten in Weiyang District of Xi'an, northwest China's Shaanxi Province, June 8, 2020. Xi'an has reopened kindergartens with opening qualifications since Monday under voluntary returning principle. (Xinhua/Zhang Bowen)

A teacher instructs a seven-step hands washing method at a classroom of a kindergarten in Weiyang District of Xi'an, northwest China's Shaanxi Province, June 8, 2020. Xi'an has reopened kindergartens with opening qualifications since Monday under voluntary returning principle. (Xinhua/Zhang Bowen)

A child receives temperature check before entering a classroom of a kindergarten in Weiyang District of Xi'an, northwest China's Shaanxi Province, June 8, 2020. Xi'an has reopened kindergartens with opening qualifications since Monday under voluntary returning principle. (Xinhua/Zhang Bowen)

Children receive physical examination before entering a kindergarten in Weiyang District of Xi'an, northwest China's Shaanxi Province, June 8, 2020. Xi'an has reopened kindergartens with opening qualifications since Monday under voluntary returning principle. (Xinhua/Zhang Bowen)