Soldier boys at Fort Dix, N.J., learn something about guns during their working hours, as they show their girlfriends at a camp dance, December 13, 1940. In front row, playing with the coin amusement gun, from left: Pvt. Tom D'Amato of West Orange; Rose Sinkewicz, behind gun site, of Trenton; Julia Ivans of Trenton, and Pvt. Vernon Landers of Kearney. Back row: Pvts. William Sargent and William Corlies of Philadelphia. (Photo by AP Photo)

A Citroen Aircross concept car is pictured during the media day at the Frankfurt Motor Show (IAA) in Frankfurt, Germany, September 15, 2015. The car show runs through September 27. (Photo by Kai Pfaffenbach/Reuters)

A Kevo smart lock is demonstrated during the 2015 International Consumer Electronics Show (CES) in Las Vegas, Nevada January 4, 2015. The lock, which opens with a smart phone App and a touch, is smart enough to know what side of the door you are on and won't accidentally unlock the door when you are inside. A new subscription service offers unlimited e-keys and other benefits, a representative said. (Photo by Steve Marcus/Reuters)

A new monorail service in Houston, Texas, ready for its inaugural service. (Photo by Evans/Three Lions/Getty Images). Circa 1950

Swedish-born actor Dolph Lundgren shows off his muscles by sweeping two women off their feet at the same time, 1986. (Photo by Dave Hogan/Hulton Archive/Getty Images)

Chinese-American actress Bai Ling is seen on October 15, 2018 in Los Angeles, CA. (Photo by Hollywood To You/Star Max/GC Images)

Rapper Future attends his “Future City” Birthday Party at Magic City on November 20, 2018 in Atlanta, Georgia. (Photo by Prince Williams/Wireimage)

Sport category, winner: Yuan Peng. Liu Bingqing and Liu Yujie are twin sisters who have studied and trained in gymnastics since their early childhood in Jining, China. (Photo by Yuan Peng/Sony World Photography Awards)