Physics teacher Zhao Chuanliang gives an online tuition for students at a local high school in Zhengzhou, capital of central China's Henan Province, Feb. 2, 2020. As schools across the country are required to postpone the opening of the spring semester, online tuition has been promoted as an effective method. (Xinhua/Li Jianan)

Physics teacher Zhao Chuanliang gives an online tuition for students at a local high school in Zhengzhou, capital of central China's Henan Province, Feb. 2, 2020. As schools across the country are required to postpone the opening of the spring semester, online tuition has been promoted as an effective method. (Xinhua/Li Jianan)

Physics teacher Zhao Chuanliang gives an online tuition for students at a local high school in Zhengzhou, capital of central China's Henan Province, Feb. 2, 2020. As schools across the country are required to postpone the opening of the spring semester, online tuition has been promoted as an effective method. (Xinhua/Li Jianan)

A staff member checks the quality of an online tuition video for students at a local high school in Zhengzhou, capital of central China's Henan Province, Feb. 2, 2020. As schools across the country are required to postpone the opening of the spring semester, online tuition has been promoted as an effective method. (Xinhua/Li Jianan)