Dancers prepare before a performance in the backstage area of the Buick exhibition during the “Auto China 2014” Beijing International Automotive Exhibition in Beijing on April 21, 2014. Leading automakers have gathered in Beijing for the kickoff of China's biggest car show, but lackluster growth and environmental restrictions in the world's largest car market have thrown uncertainty into the mix. (Photo by AFP Photo)

This picture taken on January 1, 2014 shows giant panda “Li Li” sleeping on a tree in Hangzhou Wild Animal World in Hangzhou, east China's Zhejiang province. Giant pandas, notorious for their low s*x drive, are among the world's most endangered animals. Fewer than 1,600 pandas remain in the wild, mainly in China's Sichuan province, with a further 300 in captivity around the world. (Photo by AFP Photo)

Passengers wait for a train to depart from the Hankou Railway Station in Wuhan, central China's Hubei province, Friday January 13, 2017. Officials expect that Chinese travelers will make almost 3 billion trips during the holiday travel rush that starts runs through Feb. 21. These trips include intercity flights, trains and local bus rides to villages for China's 1.4 billion people. (Photo by Chinatopix via AP Photo)

A U.S. Navy F18 fighter jet takes off from aircraft carrier USS Carl Vinson during a FONOPS (Freedom of Navigation Operation Patrol) in South China Sea, March 3, 2017. The U.S. military took journalists Friday to the carrier on routine patrol off the disputed South China Sea, sending a signal to China and American allies of its resolve to ensure freedom of navigation and overflight in one of the world's security hotspots. (Photo by Erik De Castro/Reuters)

This photo taken on October 8, 2017 shows dancers posing in formation to celebrate the upcoming Party Congress, in Rongan in China' s southern Guangxi region. China will convene its 19 th Party Congress on October 18, state media said, a key meeting held every five years where President Xi Jinping is expected to receive a second term as the ruling Communist Party' s top leader. (Photo by AFP Photo/Stringer)

Yang Juan, an employee at Goopal Group, takes a nap in her seat after lunch, in Beijing, China, April 21, 2016. Office workers sleeping on the job is a common sight in China, where a surplus of cheap labour can lead to downtime at work. But in China's technology sector, where business is growing faster than many start-up firms can hire new staff, workers burn the midnight oil to meet deadlines and compete with their rivals. Some companies provide sleeping areas and beds for workers to rest during late nights. (Photo by Jason Lee/Reuters)

In this March 15, 2012 file photo, a Chinese woman poses for photos near a sculpture depicting a Chinese yuan note at an art district in Beijing, China. China devalued its tightly controlled currency on Tuesday, August 11,2015, following a slump in trade, triggering the yuan's biggest one-day decline in a decade. The central bank said the yuan's 1.3 percent fall was due to a change aimed at making its exchange rate controls more market-oriented. But any change raises the risk of tensions with China's trading partners. (Photo by Ng Han Guan/AP Photo)

People wearing costumes attend the annual water-splashing festival to mark the New Year of the Dai minority in Jinghong, Yunnan province, April 13, 2015. (Photo by Reuters/China Daily)