A flag-raising ceremony is held at the Hou Kong Middle School in Macao, south China, Nov. 18, 2019. On Dec. 20, Macao will celebrate the 20th anniversary of its return to motherland. Over the past two decades, the special administrative region has made great strides in economic development and achieved prosperity and stability under the "one country, two systems" principle. (Xinhua/Cheong Kam Ka)