Students prepare to attend the high school entrance exam in Minhang District, east China's Shanghai, June 27, 2020. Shanghai started the high school entrance exam on Sunday with strict COVID-19 control and prevention measures. Students are required to wear face masks before entering the examination rooms and can remove it once get seated. (Photos: Xinhua)

Students queue to get their temperature checked before attending the high school entrance exam in Minhang District, east China's Shanghai, June 27, 2020. Shanghai started the high school entrance exam on Sunday with strict COVID-19 control and prevention measures. Students are required to wear face masks before entering the examination rooms and can remove it once get seated.

Students get seated at an examination room for the high school entrance exam in Minhang District, east China's Shanghai, June 27, 2020. Shanghai started the high school entrance exam on Sunday with strict COVID-19 control and prevention measures. Students are required to wear face masks before entering the examination rooms and can remove it once get seated.

Photo taken on June 27, 2020 shows a temporary observing booth for the high school entrance exam in Minhang District, east China's Shanghai. Shanghai started the high school entrance exam on Sunday with strict COVID-19 control and prevention measures. Students are required to wear face masks before entering the examination rooms and can remove it once get seated.

A teacher hugs her student before the high school entrance exam in Minhang District, east China's Shanghai, June 27, 2020. Shanghai started the high school entrance exam on Sunday with strict COVID-19 control and prevention measures. Students are required to wear face masks before entering the examination rooms and can remove it once get seated.