Aerial photo taken on April 27, 2019 shows a view of Linyi Import Commodities Wholesale City in Linyi, east China's Shandong Province. Located in mountainous areas, Linyi has been promoting logistics and commerce, and has pushed forward regional economic development over the years. (Xinhua)

　　A staff member introduces face masks at a shop of Linyi City, east China's Shandong Province, on May 10, 2019. Located in mountainous areas, Linyi has been promoting logistics and commerce, and has pushed forward regional economic development over the years. (Xinhua/Wang Kai)

　　A client checks logistics information on a phone at Jinlan logistics base in Linyi City, east China's Shandong Province, on May 10, 2019. Located in mountainous areas, Linyi has been promoting logistics and commerce, and has pushed forward regional economic development over the years. (Xinhua/Wang Kai)