Children attend a swim training session at Hangzhou Chen Jinglun Sport school Natatorium, where Chinese Olympic swimmer Sun Yang and Fu Yuanhui also trained, in Hangzhou, Zhejiang province, China, August 10, 2016. (Photo by Aly Song/Reuters)

Stray dogs stand on tombs in Diamond Hill cemetery in Hong Kong, China, 04 April 2017. According to the lunar calendar, the Qingming Festival is observed on 04 April . The Qingming Festival, also known as Tomb-Sweeping Day, is marked by Chinese people by going to the cemetery to cleaning up tombs, bring flowers, and making offerings to their ancestors. (Photo by Jerome Favre/EPA)

Cosplay fans attend the Animation Comic Games (ACG) Culture Festival in Xi'an, capital of northwest China's Shaanxi Province, May 28, 2017. The festival kicked off on Saturday, attracting lots of cosplay fans. (Photo by Liu Xiao/Xinhua)

People smear black ash with hands onto each other to wish for good luck and fortune during a traditional festival of the Yi ethnic minority in Qiubei County, Yunnan province, China July 18, 2017. (Photo by Ren Dong/Reuters/CNS)

Tibetan pilgrims walk outside the Sera Monastery in Lhasa, Tibet Autonomous Region, China, 11 September 2016. Sera Monastery is known as one of the “great three” Gelug university monasteries of Tibet founded in 1419. (Photo by How Hwee Young/EPA)

A giant panda cub falls from the stage while 23 giant pandas born in 2016 seen on a display at the Chengdu Research Base of Giant Panda Breeding in Chengdu, Sichuan province, China, September 29, 2016. (Photo by Rex Features)

A truck is seen in a hole after part of the structure of a bridge collapsed into a river in Changchun, Jilin province May 29, 2011. Two truck passengers were injured, while the cause of the accident is still under investigation, local media reported. (Photo by Reuters/China Daily)

American free climber Dean Potter walks on a 41-meter-long and two-centimeter-wide slackline over Enshi Grand Canyon at an altitude of 1,800m on April 22, 2012 in Enshi, Hubei Province of China. Potter successfully finished the lone slackline walk in about three minutes without taking any protective measures. (Photo by ChinaFotoPress/ChinaFotoPress)