Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Lui Siu Wai)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Lui Siu Wai)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Lui Siu Wai)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Lui Siu Wai)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Lui Siu Wai)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Lui Siu Wai)

Photo taken on Dec. 22, 2019 shows drones performing during a firework show in south China. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Cheong Kam Ka)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Cheong Kam Ka)

Photo taken on Dec. 22, 2019 shows drones performing during a firework show in south China. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Cheong Kam Ka)

Photo taken on Dec. 22, 2019 shows drones performing during a firework show in south China. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Cheong Kam Ka)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Cheong Kam Ka)

Fireworks explode over the sky in south China's Macao, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Cheong Kam Ka)

Fireworks explode over the sky in Zhuhai, south China's Guangdong Province, Dec. 22, 2019. Macao and its neighboring city Zhuhai jointly held a firework show to celebrate the 20th anniversary of Macao's return to the motherland on Sunday. (Xinhua/Huang Guobao)