Teachers put new textbooks on desks in advance for students of grade nine at a school in Yunyan District of Guiyang City, southwest China's Guizhou Province, March 15, 2020. Schools in Guiyang have taken strict measures against the COVID-19, ensuring a safe new semester for students. [Photo/Xinhua]

Guided paths are set up in advance for students of grade nine at a school in Yunyan District of Guiyang City, southwest China's Guizhou Province, March 15, 2020. Schools in Guiyang have taken strict measures against the COVID-19, ensuring a safe new semester for students. [Photo/Xinhua]

A teacher puts new textbooks on desks in advance for students of grade nine at a school in Yunyan District of Guiyang City, southwest China's Guizhou Province, March 15, 2020. Schools in Guiyang have taken strict measures against the COVID-19, ensuring a safe new semester for students. [Photo/Xinhua]

A teacher transports disinfectant at a middle school in Guiyang City, southwest China's Guizhou Province, March 15, 2020. Schools in Guiyang have taken strict measures against the COVID-19, ensuring a safe new semester for students. [Photo/Xinhua]

Teachers put new textbooks on desks in advance for students of grade nine at a school in Yunyan District of Guiyang City, southwest China's Guizhou Province, March 15, 2020. Schools in Guiyang have taken strict measures against the COVID-19, ensuring a safe new semester for students. [Photo/Xinhua]

Teachers put new textbooks on desks in advance for students of grade nine at a school in Guiyang City, southwest China's Guizhou Province, March 15, 2020. Schools in Guiyang have taken strict measures against the COVID-19, ensuring a safe new semester for students. [Photo/Xinhua]