Aerial photo taken on Aug. 2, 2021 shows an external view of the Deqing tunnel of the Guiyang-Nanning high-speed railway in Hechi, south China's Guangxi Zhuang Autonomous Region. The 6.61-km-long Deqing tunnel was drilled through on Tuesday. It is a critical control project in the construction of the Guiyang-Nanning high-speed railway, which is expected to put into operation by the end of 2023. (Xinhua/Liu Lingyi)
