Two Bulgarian tourists pose in front of the Eiffel Tower in Paris on their last day in the capital on March 24, 2014. (Photo by Franck Fife/AFP Photo)

Eight-year-old Niu Dongfang trains at the No. 2 Beijing Shuangqiao School January 13, 2005 in Beijing, China. Most of students in the gymnastics school have to study more than five years from as young as age six before they become athletes. (Photo by Guang Niu/Getty Images)

Space shuttle Atlantis (R) remains docked to the International Space Station photographed by NASA astronaut Ronald Garan during a planned six-and-a-half-hour spacewalk July 12, 2011 in space. Space shuttle Atlantis has embarked on a 12-day mission to the International Space Station where it will deliver the Raffaello multi-purpose logistics module packed with supplies and spare parts. This was the final mission of the space shuttle program, which began on April 12, 1981 with the launch of Colombia. (Photo by NASA via Getty Images)

People participate in a winter fishing event in Changchun, Jilin province, China, December 25, 2016. Picture taken December 25, 2016. (Photo by Reuters/Stringer)

People look at home-made armoured vehicle look-alikes on a street in Shenyang, Liaoning province, November 12, 2014. A man surnamed Zhang and his friends converted two cars into these two vehicles, for his son, and will be displaying them on show at a local park. The cannons on the vehicles can fire paintballs and smoke shells, local media cited Zhang as saying. (Photo by Reuters/Stringer)

Typhoon Bopha moves toward the Philippines, observed from the ISS, on December 2, 2012. (Photo by AP Photo/NASA via The Atlantic)

Professor Xie Yong works on an art installation of a beaver, which is made out of plastic and around 300,000 needles, in Shenyang, Liaoning province, July 23, 2013. The needles, according to Xie, represent the pain felt by animals when their fur is taken off to produce clothing. (Photo by Reuters/Stringer)

Homeless people queue to get free hot food organized by social services during frost winter day in-Kiev on December 18, 2012. Nineteen people died of exposure in Ukraine in the last 24 hours amid temperatures of minus 20 degrees Celsius (minus 4 degrees Fahrenheit), bringing the toll this month to 37, the health ministry said Tuesday. (Photo by Sergei Supinsky/AFP Photo)