A view of the spectacular colour of clouds at sunset on January 17, 2005 in Beijing, China. (Photo by China Photos/Getty Images)

Wang uses a mobile phone as she take a rest in her room at the accommodation where patients and their family members stay while seeking medical treatments in Beijing, China, June 23, 2016. Wang, who suffers from cervical cancer, came from Inner Mongolia to seek treatment at a specialist hospital in Beijing. (Photo by Kim Kyung-Hoon/Reuters)

Models painted in camouflage colours to blend in with the background pose for Chinese artist Liu Bolin's artwork “Dongji”, or Winter Solstice, on the second day after China's capital Beijing issued its second ever “red alert” for air pollution, in Beijing, China, December 20, 2015. In this artwork, Liu wants to express his concerns about China and its people, including air pollution problem, Liu told Reuters. (Photo by Kim Kyung-Hoon/Reuters)

A model falls over on the runway during the SECCRY Hu Sheguang Collection 2014 Show during Mercedes-Benz China Fashion Week, March 30, 2014, in Beijing. (Photo by Lintao Zhang/Getty Images)

Robot Xian'er is placed in the main building of Longquan Buddhist temple for photographs by the temple's staff, on the outskirts of Beijing, April 20, 2016. (Photo by Kim Kyung-Hoon/Reuters)

A girl types on a computer as she demonstrates the interior of the new Volvo S90 during the Auto China 2016 auto show in Beijing April 25, 2016. (Photo by Damir Sagolj/Reuters)

In this Sunday, March 5, 2017, photo, hospitality staff take souvenir photos in front of the Great Hall of the People where the National People's Congress is held in Beijing. (Photo by Andy Wong/AP Photo)

A female honor guard has lipstick applied as they prepare for an official welcoming ceremony outside the Great Hall of the People in Beijing, China on June 11, 2014. (Photo by Jason Lee/Reuters)