Staff members greet the graduates at Burlingame High School in San Mateo county, the United States, May 22, 2020. The school held drive-thru graduation for the class of 2020 due to COVID-19. (Xinhua/Wu Xiaoling)

Staff members greet the graduates at Burlingame High School in San Mateo county, the United States, May 22, 2020. The school held drive-thru graduation for the class of 2020 due to COVID-19. (Xinhua/Wu Xiaoling)

Staff members greet the graduates at Burlingame High School in San Mateo county, the United States, May 22, 2020. The school held drive-thru graduation for the class of 2020 due to COVID-19. (Xinhua/Wu Xiaoling)

Photo taken on May 22, 2020 shows a balloons arch at Burlingame High School in San Mateo county, the United States. The school held drive-thru graduation for the class of 2020 due to COVID-19. (Xinhua/Wu Xiaoling)

Photo taken on May 22, 2020 shows posters at Burlingame High School in San Mateo county, the United States. The school held drive-thru graduation for the class of 2020 due to COVID-19. (Xinhua/Wu Xiaoling)