Combination photo taken on June 17, 2019 (up) and on undated day in the past shows the change of the site of Qianmalong coal mine in Tianzhu Tibetan Autonomous County in Wuwei City, northwest China's Gansu Province. Friday marks China's National Tree Planting Day. With the efforts of volunteers across the country, green lands has covered more areas of China and the eco-friendly development concept is seeded in people's heart. (Xinhua/Fan Peishen)