Students celebrate their A-level results at King Edward VI High School for Girls in Birmingham, England on August 18, 2016. The proportion of top grades achieved by A-level students across the UK has fallen for a fifth year in a row, and girls have caught up with boys in attaining A* grades. (Photo by Joe Giddens/PA Wire)

The ruins of a castle stand above the town of Rocca Calascio, close to Santo Stefano di Sessanio in the province of L'Aquila in Abruzzo, inside the national park of the Gran Sasso e Monti della Laga, Italy, September 7, 2016. (Photo by Siegfried Modola/Reuters)

This picture taken on October 20, 2016 shows students practising wushu at the Tagou martial arts school in Dengfeng. China is investing hugely in football training and has vowed to have 50 million school- age players by 2020, as the ruling Communist party eyes “football superpower” status by 2050. (Photo by Nicolas Asfouri/AFP Photo)

A woman tour skates on the frozen lake of Orlangen, south of Stockholm, Sweden, on December 23, 2016. Tour skating is recreational long distance ice skating on natural ice particularly popular in the Nordic countries. (Photo by Tobias Roestlund/AFP Photo/TT News Agency)

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

Nur Elita, an Acehnese woman, screams during caning as part of her sentence in the courtyard of Baiturrahman mosque in Banda Aceh, Indonesia's Aceh province December 28, 2015. Nur Elita received five strokes of the cane for having pre-marital s*x with her boyfriend, according to local media. Aceh is the only province in Indonesia, the world's most populous Muslim country, where Islamic law is implemented, according to local media. (Photo by Junaidi Hanafiah/Reuters)

Opossums on their mothers back at a game reserve in Central Minnesota, USA, on September 2, 2013. (Photo by Caters News Agency)

«Mignon 2». A.E.G., Berlin, Germany, 1905. Despite its unusual appearance, the Mignon typewriter is of a very clever design, giving a smooth and fast operation for typing. (Photo and caption by Martin Howard/Martin Howard Collection)