Photo taken on April 11, 2019 shows the scenery of the Mutianyu Great Wall in Beijing, capital of China. (Xinhua/Hou Dongtao)

　　Photo taken on April 10, 2019 shows the scenery of the Mutianyu Great Wall in Beijing, capital of China. (Xinhua/Hou Dongtao)

　　Photo taken on April 11, 2019 shows the scenery of the Mutianyu Great Wall in Beijing, capital of China. (Xinhua/Hou Dongtao)

　　Photo taken on April 11, 2019 shows the scenery of the Mutianyu Great Wall in Beijing, capital of China. (Xinhua/Hou Dongtao)

　　Photo taken on April 10, 2019 shows the scenery of the Mutianyu Great Wall in Beijing, capital of China. (Xinhua/Hou Dongtao)

　　Photo taken on April 11, 2019 shows the scenery of the Mutianyu Great Wall in Beijing, capital of China. (Xinhua/Zhang Chenlin)