Photo taken on April 18, 2020 shows a view of Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)

Photo taken on April 18, 2020 shows a view of Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)

Aerial photo taken on April 18, 2020 shows a zigzag road on Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)

Photo taken on April 18, 2020 shows a view of Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)

Photo taken on April 18, 2020 shows a view of Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)

Aerial photo taken on April 18, 2020 shows a view of Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)

Aerial photo taken on April 18, 2020 shows a view of Jiuxian Mountain in Wulian County of Rizhao City, east China's Shandong Province. (Xinhua/Wang Kai)