Employees work at a sorting centre of Zhongtong (ZTO) Express ahead of the Singles Day shopping festival, Chaoyang District, Beijing, November 8, 2015. On China's giant Singles Day internet shopping festival, the country's delivery firms are stretched so thin that they are looking for tie-ups, listings and new investors to husband their resources. (Photo by Jason Lee/Reuters)

A truck lays overturned onto a car following strong winds at a Kurnell industrial park after a rare tornado hit the Sydney suburb December 16, 2015. The tornado hit Sydney on Wednesday with destructive winds above 200 km an hour (125 mph) and cricket ball-sized hail, bringing down trees and power lines, tearing off roofs, overturning vehicles and causing flash flooding. (Photo by Jason Reed/Reuters)

Chinese women holding toy guns dance for a revolutionary song during their daily exercise at a square outside a shopping mall in Beijing, June 29, 2014. About 30 local residents formed this “Nanguan” art group that enjoys performing to revolutionary songs and dance performances as part of their daily fitness activities at night. (Photo by Jason Lee/Reuters)

Australian knight Philip Leitch (R) has a floral basket on his helmet smashed by an opponent at the St Ives Medieval Fair in Sydney, one of the largest of its kind in Australia, September 25, 2016. (Photo by Jason Reed/Reuters)

Mel Harris shouts whilst a pick up truck belches smoke on the final night of the Deni Ute Muster in Deniliquin, New South Wales, Australia, October 1, 2016. In the small rural town of Deniliquin, on the edge of Australia's vast outback, around 20,000 “ute” lovers gathered in the mud to champion a national treasure deemed surplus to requirements by the big car manufacturers. (Photo by Jason Reed/Reuters)

A string is used to ensure that the skirts of female members of the honour guard are in the same height from the ground as they prepare for a welcoming ceremony for Congo Republic President Denis Sassou Nguesso outside the Great Hall of the People in Beijing, China, July 5, 2016. (Photo by Jason Lee/Reuters)

January 22, 2017; Atlanta, GA, USA; Atlanta Falcons cheerleaders take a picture in the confetti after the game against the Green Bay Packers in the 2017 NFC Championship Game at the Georgia Dome. Atlanta defeated Green Bay 44-21. (Photo by Jason Getz/USA TODAY Sports)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)