Photo taken on Dec. 10, 2019 shows a light rail train in south China's Macao Special Administrative Region. The light rail in Macao opened to public on Tuesday. (Xinhua/Cheong Kam Ka)

Photo taken on Dec. 10, 2019 shows light rail trains in south China's Macao Special Administrative Region. The light rail in Macao opened to public on Tuesday. (Xinhua/Cheong Kam Ka)

Photo taken on Dec. 10, 2019 shows a light rail train running in south China's Macao Special Administrative Region. The light rail in Macao opened to public on Tuesday. (Xinhua/Cheong Kam Ka)

Photo taken on Dec. 10, 2019 shows the inside view of a light rail train in south China's Macao Special Administrative Region. The light rail in Macao opened to public on Tuesday. (Xinhua/Cheong Kam Ka)

Photo taken on Dec. 10, 2019 shows a light rail train running in south China's Macao Special Administrative Region. The light rail in Macao opened to public on Tuesday. (Xinhua/Cheong Kam Ka)