A line of soldiers firing handguns during a training session, circa 1920. (Photo by Keystone). P.S. All pictures are presented in high resolution.

A U.S. Marine leads training on a shooting range in France in an undated photo taken during the First World War. (Photo by Reuters/Courtesy Library of Congress)

Paramilitary policemen take part in a summer training in Shenzhen, Guangdong province, China, June 27, 2016. (Photo by Reuters/China Daily)

Employees work on an electric train assembly line at the “Stadler Minsk” plant in Fanipol, Belarus February 10, 2016. (Photo by Vasily Fedosenko/Reuters)

Paramilitary policemen take part in a training in Chaohu, Anhui province, China December 28, 2015. (Photo by Reuters/China Daily)

In a photo taken on October 7, 2020 a woman holds two dogs as she waits for a train in Suncheon. (Photo by Ed Jones/AFP Photo)

A man sleeps in a subway train in New York city on August 1, 2024. (Photo by Charly Triballeau/AFP Photo)

A five-month-old female slender loris waits to be given her first health check by the veterinary team at London Zoo on July 21, 2011 in London, England. Two female baby slender lorises, who are yet to be named, were given health checks, their s*x determined and micro-chipped. Slender Loris is the common name for the strepsirrhine primates who are nocturnal and originate from India, Sri Lanka, and southeast Asia. London Zoo supports conservation of lorises in Sri Lanka, where populations are thought to be under threat from deforestation. (Photo by Christopher Furlong/Getty Images)