Images of former U.S. President Barack Obama speaking in a video feed of the 2020 Democratic National Convention are displayed on screens in Arlington, Virginia, the United States, on Aug. 19, 2020. (Xinhua/Liu Jie)

Images of U.S. House Speaker Nancy Pelosi speaking in a video feed of the 2020 Democratic National Convention are displayed on screens in Arlington, Virginia, the United States, on Aug. 19, 2020. (Xinhua/Liu Jie)

Images of former U.S. Secretary of State Hillary Clinton speaking in a video feed of the 2020 Democratic National Convention are displayed on screens in Arlington, Virginia, the United States, on Aug. 19, 2020. (Xinhua/Liu Jie)