Aerial photo taken on Dec. 12, 2019 shows a test train running on the Shashangou grand bridge in Kazak Autonomous County of Aksay, northwest China's Gansu Province. The grand bridge is a difficulty in engineering on the railway linking Dunhuang city, northwest China's Gansu Province, and Golmud city, northwest China's Qinghai Province, which is scheduled to be put into operation in December. (Xinhua/Fan Peishen)