The upper part (file) of this combo photo taken by Zhou Jiaguo shows a volunteer doctor examining an aged woman at a community in Shenzhen, south China's Guangdong Province. The lower part of the combo photo taken by Mao Siqian on May 8, 2018 shows a volunteer helping a passenger use a smartphone-generated QR code to buy ticket in Shenzhen Metro. This year marks the 40th anniversary of China's reform and opening-up policy. Over the past four decades, Shenzhen has developed from a small fishing village to a metropolis. (Xinhua)