In this aerial photo taken on June 22, 2018, workers prepare steel girders for the construction of a bridge across the Yuanjiang River along the China-Laos railway project in Yuxi, southwest China's Yunnan Province. Linking Yuxi in southwest China and the Lao capital Vientiane, the China-Laos railway is expected to be fully operational in December 2021. (Xinhua/Hu Chao)