Photo taken with a mobile phone shows a black swan in a lake at the Summer Palace in Beijing, capital of China, March 17, 2019. (Xinhua/Zhang Haofu)

Photo taken with a mobile phone shows tourists walking inside the Temple of Heaven in Beijing, capital of China, March 16, 2019. (Xinhua/Zhang Haofu)

Photo taken with a mobile phone at Jingshan Park shows the sunset in Beijing, capital of China, March 16, 2019. (Xinhua/Zhang Haofu)