Visitors watch the stamps showing China's science and technology achievements during the "China-Great Change" stamp exhibition in Leuven, Belgium, Dec. 11, 2018. A large-scale stamp exhibition was opened Tuesday at Belgium's University of Leuven to commemorate the 40th anniversary of China's reform and opening up. Themed "China - Great Change", the exhibition, showcasing 188 stamps, aims to offer a glimpse into the significant changes that have transpired in China over the last four decades. (Xinhua/Zheng Huansong)