US President Donald Trump' s daughter and senior White House adviser Ivanka Trump (2nd R) poses for a photo on a balcony of the VIP tent at the Olympic sliding centre with US army luge athletes Taylor Morris (L) and Matt Mortensen (2nd L), and US women’s bobsleigh silver medallist Lauren Gibbs (R) before the ski jump tower at the men' s four- man bobsleigh event of the Pyeongchang Winter Olympic games in Pyeongchang on February 25, 2018. (Photo by Eric Gaillard/Reuters)

Undated David Yarrow handout photo of a gorilla as the self-taught wildlife photographer promotes his book, Encounter. (Photo by David Yarrow/Clearview/PA Wire)

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)

A young couple rest in a football field after a forest fire devastated Santa Olga, 240 kilometres south of Santiago, on January 26, 2017. Six people – among them four firefighters and two police – have now been killed battling vast forest fires in central Chile, officials said Wednesday. Multiple blazes have ravaged 238,000 hectares (588,000 acres) and are growing, the National Forestry Corporation said in a statement. (Photo by Pablo Vera Lisperguer/AFP Photo)

Two men play golf with a tennis ball as a snowstorm sweeps through Times Square, Tuesday, March 14, 2017, in New York. (Photo by Mark Lennihan/AP Photo)

Demonstrators clash with members of the Bolivarian National Police as protests continue in Caracas, Venezuela, 20 April 2017. The Bolivarian National Guard, using tear gas, tried to disperse protests against the government of Venezuelan President Nicolas Maduro. (Photo by Miguel Gutierrez/EPA)

A student from “the cliff village” in Atule'er climbs newly-constructed steel ladders after school to go home for holidays, in Liangshan Sichuan province, China, November 19, 2016. The steel ladders which replaced the unsafe vine ladders shortened the time taken for the children to go home, from three hours to two. (Photo by Reuters/Stringer)