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. [Photo by Zhang Bowen/Xinhua]

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. [Photo by Zhang Bowen/Xinhua] 

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. [Photo by Zhang Bowen/Xinhua]