Tibetan students play at a class break at the Xiangnong primary school on April 15, 2005 in Kangding County of Ganzi Tibetan Autonomous Prefecture, Sichuan Province, southwest China. There is only one teahcer in the Tagong Village, 12 Tibetan students get free education from him in Xiangnong primary school. (Photo by China Photos/Getty Images)

Dried and shrivelled corpses, some fully clothed and some in coffins, line the wall of a vault of the Pantheon Cemetery on the summit of Cerro del Trozado in Mexico. They were removed from the crypts because of non-payment of cemetery fees. The hot dry air stopped the bodies from rotting. Most of them were placed here between the turn of the century and WW I. (Photo by Three Lions/Getty Images). Circa 1955

The Hot air balloon is flying at the Warsteiner International Hot Air Balloon Show in the Arnsberger Forest National Park on September 2, 2011 near Warstein, Germany. Approximately 200 hot air balloons are scheduled to take part in the nine-day event sponsored by the Warsteiner brewery. (Photo by Mathis Wienand/Getty Images)

Former Ministry of Defence motorbikes (guide price £650 to £1250) being serviced ready for potential buyers on August 12, 2011 in Colsterworth, England. Witham LTD sells a variety of former MOD equipment and vehicles to foreign countries, domestic companies and private individuals. (Photo by Matthew Lloyd/Getty Images)

Women, wearing traditional “ao dai” dress, pose for a photo next to peach blossom flowers ahead of Vietnamese “Tet” (the lunar new year festival) in a field in Hanoi January 22, 2017. (Photo by Reuters/Kham)

Philippine President Rodrigo Duterte looks at Miss Universe candidates at the presidential palace in Manila, Philippines January 23, 2017. (Photo by Erik De Castro/Reuters)

Marek Jama performs during the gala of the 41 st Monte- Carlo International Circus Festival in Monaco on January 25, 2017. (Photo by Eric Gaillard/AFP Photo)

Men hang at the back of a truck loaded with farm produce along a road in Ikeja district in the commercial capital Lagos, Nigeria December 19, 2016. (Photo by Akintunde Akinleye/Reuters)