An AH-64D Apache attack helicopter flies in front of a wall of fire during the South Carolina National Guard Air and Ground Expo at McEntire Joint National Guard Base, South Carolina, U.S. on May 6, 2017. (Photo by Jorge Intriago/Reuters/Courtesy Air National Guard)

Students training to be flight attendants hold books on their heads, chopsticks in their mouths, and papers in between their knees, as they take part in a standing posture practice at a vocational school in Shijiazhuang, Hebei province, China May 4, 2017. (Photo by Reuters/Stringer)

UFC women's bantamweight champion Holly Holm and Miesha Tate face off during the UFC 196 weigh ins at the MGM Grand Garden Arena in Las Vegas on Friday, March 4, 2016. (Photo by L.E. Baskow/Las Vegas Sun via AP Photo)

A worker loads palm fruit at a palm oil plantation in North Mamuju regency, West Sulawesi province, Indonesia March 10, 2016 in this photo taken by Antara Foto. (Photo by Sahrul Manda Tikupadang/Reuters/Antara Foto)

Teenagers on roller skates hold on to each other as they are pulled by a vintage car to move along a street in Havana, Cuba March 19, 2016. (Photo by Ivan Alvarado/Reuters)

Serena Williams of the U.S. serves during her first round match against Italy's Camila Giorgi at the Australian Open tennis tournament at Melbourne Park, Australia, January 18, 2016. (Photo by Jason O'Brien/Reuters)

Military items for women are seen in a store in Erbil, Iraq January 24, 2017. (Photo by Marius Bosch/Reuters)

A girl smiles as her hair is blown by a strong wind in the Chinatown area in Yokohama, near Tokyo, Friday, January 27, 2017. (Photo by Koji Sasahara/AP Photo)