A man performs a split as he practices Kung Fu at Beihai Park in Beijing, China August 20, 2017. (Photo by Reuters/China Stringer Network)

A member of the Air Force's Wings of Blue Parachute Demonstration Team salutes as he jumps out of an aircraft, during the opening ceremony of Aviation Nation 2017 Nellis Air and Space Expo at Nellis Air Force Base, Nev., November 10, 2017. (Photo by Senior Airman Kevin Tanenbaum/Reuters/U.S. Air Force)

These Arab recruits line up in a barracks square in the British Mandate of Palestine, on December 28, 1940, for their first drill under a British solider. Some 6,000 Palestinian Arabs signed up with the British Army during the course of World War II. (AP Photo)

A boy jumps from a swing during sunset in Valras-Plage, southern France December 29, 2014. (Photo by Yves Herman/Reuters)

Chinese relative of a missing passenger on Malaysia Airlines flight MH370 reacts as she weeps outside the main gate of the Lama Temple on March 8, 2015 in Beijing, China. Foreign and local media were prevented by Chinese police from covering the relatives visit to the temple where they tried to pray .There were 239 people on board the flight when it disappeared March 8, 2014 en route from Kuala Lumpur to Beijing. After one year and an exhaustive search, investigators still have no clue as to the whereabouts of the missing airliner. (Kevin Frayer/Getty Images)

A Monster Jam truck performs a back flip during the first-ever monster truck event in Beijing's iconic “Bird's Nest” National Stadium on Saturday, July 29, 2017. (Photo by Ng Han Guan/AP Photo)

A massive, 8 metre tall sculpture of Marilyn Monroe, frozen with her dress blowing up, was on display at a shopping mall in downtown Dalian city, northeast China's Liaoning province, on Tuesday, November 14, 2017. The sculpture is a replica of Seward Johnson's Forever Marilyn in Chicago. (Photo by Imagine China/Rex Features/Shutterstock)

Riot police clash with demonstrators protesting against proposed pension reforms outside the Congress in Buenos Aires on December 18, 2017. Protesters angry at proposed pension and welfare reforms attacked police close to Argentina's congress building in Buenos Aires on Monday, the second protest in a week to turn violent. Activists lobbed stones, bottles and firecrackers at police as huge crowds demonstrated against pension reforms proposed by the center-right government of President Mauricio Macri. (Photo by Eitan Abramovich/AFP Photo)