A worker fastens a screw at the construction site of the Monei River bridge of the China-Laos railway in Pu'er City, southwest China's Yunnan Province, April 12, 2019. Linking Yuxi City in Yunnan and the Lao capital Vientiane, the China-Laos railway is expected to be fully operational by the end of 2021. (Xinhua/Qin Qing)