People look at the Pillar of Shame, a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

A member (C) of the University of Hong Kong student union speaks to the media before cleaning the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

Members of the University of Hong Kong student union observe a moment of silence before cleaning the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

Members of the University of Hong Kong student union clean the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

Members of the University of Hong Kong student union clean the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

Members of the University of Hong Kong student union clean the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

Members of the University of Hong Kong student union clean the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)

A woman (R) lays flowers at the 'Pillar of Shame', a monument that commemorates the victims of the 1989 Tiananmen Square crackdown, at the University of Hong Kong on June 4, 2021. (Photo by ISAAC LAWRENCE / AFP)