Residents wearing face masks are seen in Hong Kong, south China, Dec. 23, 2020. (Photos: Xinhua)

Residents walk on the street in Hong Kong, south China, Dec. 21, 2020.

Residents wearing face masks are seen in Hong Kong, south China, Dec. 21, 2020.

A woman arranges seafood in a shop in Hong Kong, south China, Dec. 23, 2020.

Residents wearing face masks take a subway in Hong Kong, south China, Dec. 23, 2020.

People exercise in a park in Hong Kong, south China, Dec. 23, 2020.

A woman walks in a park in Hong Kong, south China, Dec. 23, 2020.

Residents wearing face masks are seen in Hong Kong, south China, Dec. 23, 2020.