Postman Lao Chan Koi, who has been working for four years, delivers a mail in Macao, south China, Dec. 5, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability. (Photos: Xinhua/Cheong Kam Ka)

Pui va Middle School teacher Un Kam Sok, who has been working for 20 years, is seen at her office in Macao, south China, Nov. 26, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Cheang Kit Long, a director of garden department at the Galaxy Hotel who has been working for two years, prunes plants at the hotel in Macao, south China, Dec. 3, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Postman Lao Chan Koi, who has been working for four years, walks to deliver mails in Macao, south China, Dec. 5, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Tang Kei Kuan, a staff member at the Macao International Airport who has been working for three years, is seen at the airport in Macao, south China, Nov. 25, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Pui va Middle School teacher Un Kam Sok, who has been working for 20 years, is seen at a classroom in Macao, south China, Nov. 26, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Tang Kei Kuan, a staff member at the Macao International Airport who has been working for three years, guides the taxiing of a plane in Macao, south China, Nov. 25, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Cheang Kit Long, a director of garden department at the Galaxy Hotel who has been working for two years, stands near a parterre at the hotel in Macao, south China, Dec. 3, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Fong Chi Kwan, a taxi driver of the Macao Radio Taxi Services Ltd. who just got into the company, drives in Macao, south China, Dec. 3, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Fong Chi Kwan, a taxi driver of the Macao Radio Taxi Services Ltd. who just got into the company, poses for a photo beside his car in Macao, south China, Dec. 3, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Chang Lat Seng, a staff member of the restaurant for teaching at the Macao Institute for Tourism Studies who has been working for 22 years, serves a customer at the restaurant in Macao, south China, Nov. 26, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.

Chang Lat Seng, a staff member of the restaurant for teaching at the Macao Institute for Tourism Studies who has been working for 22 years, is seen at the restaurant in Macao, south China, Nov. 26, 2019. Since its return to the motherland 20 years ago, Macao has made great strides in economic development and achieved prosperity and stability.