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)

In this April 1, 2002, file photo, Mike Cole, of Jenkintown, Pa., right, performs a kick-flip over a trash can with his skateboard as tourists pose for photos in front of artist Robert Indiana's sculpture in John F. Kennedy Plaza, also known as Love Park, in Philadelphia. Granite slabs from Philadelphia's famed Love Park, a skateboarding mecca though for a long stretch an illegal one, are being shipped in 2017 to the city of Malmo, Sweden, nearly 4,000 miles away, for use in construction of a skate park there. (Photo by Douglas Bovitt/AP Photo)

A herd of elephants cross a road that passes through the flooded Kaziranga National Park in the northeastern state of Assam, India, July 12, 2017. (Photo by Anuwar Hazarika/Reuters)

Visitors pose for pictures under blooming cherry blossoms at a botanical garden in Nanjing, capital of China’s eastern Jiangsu province on March 15, 2019. (Photo by Reuters/China Stringer Network)

A Broto dancer prepares himself in a disused house of Bambari, in the centre of Central African Republic, before performing on March 14, 2019. The Broto, belonging to the Banda ethnic group, are known for their traditional dances accompanied by heavy horns made of tree roots. Today this tradition falls into disuse and its history is now forgotten by the new generations. (Photo by Florent Vergnes/AFP Photo)

In this Tuesday, April 16, 2019, file photo, a visitor posing for a photo walks though azalea blossoms at Nezu Shrine during a day of mild spring weather in Tokyo. Nezu Shrine is one of the oldest shrines in Tokyo. (Photo by Eugene Hoshiko/AP Photo/File)

Women carry pitchers after filling them with water from a hand pump to their houses in Thane district in the western state of Maharashtra, India, May 30, 2019. (Photo by Francis Mascarenhas/Reuters)

8-year-old Fulani boy Suleiman Yusuf drinks milk from a cow belonging to his father cattle near his family's house at Kachia Grazing Reserve, Kaduna State, Nigeria, on April 16, 2019. Kachia Grazing Reserve is an area set aside for the use of Fulani pastoralist and it is intended to be the foci of livestock development. The purpose for the grazing reserves is the settlement of nomadic pastoralists and inducement to sedentarisation through the provision of land for grazing and permanent water as way to avoid conflict. (Photo by Luis Tato/AFP Photo)