Photo shows a closed public school in New York, the United States, Sept. 1, 2020. New York Mayor Bill de Blasio announced Tuesday that the city's public school system's reopening will be postponed. (Xinhua/Wang Ying)

People walk past a public school in New York, the United States, Sept. 1, 2020. New York Mayor Bill de Blasio announced Tuesday that the city's public school system's reopening will be postponed. (Xinhua/Wang Ying)

People walk past a public school in New York, the United States, Sept. 1, 2020. New York Mayor Bill de Blasio announced Tuesday that the city's public school system's reopening will be postponed. (Xinhua/Wang Ying)

A man walks past a public school in New York, the United States, Sept. 1, 2020. New York Mayor Bill de Blasio announced Tuesday that the city's public school system's reopening will be postponed. (Xinhua/Wang Ying)