Ukrainian Air Force officers attend a graduation ceremony at the National University of Defence of Ukraine in Kiev, April 24, 2015. (Photo by Gleb Garanich/Reuters)

Young gymnasts practice pull-up on a bar at a gymnasium of a sports school in Jiaxing, Zhejiang province April 11, 2015. (Photo by William Hong/Reuters)

Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul April 17, 2010. (Photo by Lucas Jackson/Reuters)

Yaks head towards the Everest base camp in Solukhumbu District April 28, 2014. (Photo by Navesh Chitrakar/Reuters)

The Lamb National takes place for the racegoers at Ascot Racecourse on April 2, 2017 in Ascot, England. (Photo by Alan Crowhurst/Getty Images)

Singer Taylor Swift poses at the 2016 iHeartRadio Music Awards in Inglewood, California, April 3, 2016. (Photo by Danny Moloshok/Reuters)

Rugby Union, Hong Kong Sevens, Hong Kong Stadium on April 9, 2016: A fan wearing a mask is hugged. (Photo by Bobby Yip/Reuters)

A participant has his body painted before a regional bodybuilding championship in Stavropol, southern Russia, April 10, 2016. (Photo by Eduard Korniyenko/Reuters)