File photo taken on July 24, 2011 shows the scenery of karst landform in Dacai Township under Maonan Autonomous County of Huaijiang, south China's Guangxi Zhuang Autonomous Region. The World Heritage Committee on Monday inscribed an extension of South China Karst, a natural World Heritage Site since 2007, into the UNESCO's World Heritage List. (Photo by Wang Xiufa/Xinhua)

This picture taken on September 9, 2014 shows a waiteress handing over food to customers at a prison themed restaurant in Tianjin. As more themed restaurants are popular in China, a “prison style” restaurent in Tianjin is aimed at reminding people to observe the law and to be good citizens. (Photo by Wang Zhao/AFP Photo)

A boy rides on a snow wagon towed by a robot dressed as a Teddy bear, which only moves forward by moving its legs, during the Ice and snow carnival at Taoranting park in Beijing February 9, 2015. (Photo by Kim Kyung-Hoon/Reuters)

People pass a suitcase as they line up to enter a railway station in Beijing, February 15, 2015. Chinese Ministry of Transport said a total of 2.807 billion trips are expected to be made during the 40-day Spring Festival travel rush, which started on February 4 and will last until March 16, Xinhua News Agency reported. (Photo by Reuters/Stringer)

A migrant carries his belongings as he arrives at the Beijing railway station to catch a train in Beijing, Friday, February 13, 2015. (Photo by Andy Wong/AP Photo)

Chinese women holding toy guns dance for a revolutionary song during their daily exercise at a square outside a shopping mall in Beijing, June 29, 2014. About 30 local residents formed this “Nanguan” art group that enjoys performing to revolutionary songs and dance performances as part of their daily fitness activities at night. (Photo by Jason Lee/Reuters)

A street cleaner demonstrates his martial arts skills in front of a closed shop near Beijing's Tiananmen Square September 2, 2015 as the capital prepares for tomorrow's parade. (Photo by Damir Sagolj/Reuters)

Chinese workers maintain an Animatronic Dinosaurs at Gengu Dinosaurs Science and Technology company on November 13, 2019 in Zigong, Sichuan Province, China. There are hundreds of simulated dinosaur manufacturers in Zigong City. It is the largest simulated dinosaur manufacturing in China. It accounts for 95% of mainland China's production and 85% of the world's total. Its products are exported to more than 100 countries. (Photo by Lintao Zhang/Getty Images)