A worker works at the construction site of an aero-engine maintenance base in Haikou, capital city of south China's Hainan Province, Jan. 14, 2021.Photo:Xinhua

A worker works at the construction site of an aero-engine maintenance base in Haikou, capital city of south China's Hainan Province, Jan. 14, 2021.Photo:Xinhua

A worker works at the construction site of an aero-engine maintenance base in Haikou, capital city of south China's Hainan Province, Jan. 14, 2021.Photo:Xinhua