U.S. Marines, left, and South Korean Marines, wearing blue headbands on their helmets, take positions after landing on the beach during the joint military combined amphibious exercise, called Ssangyong, part of the Key Resolve and Foal Eagle military exercises, in Pohang, South Korea, Saturday, March 12, 2016. North Korea said Saturday its military is ready to pre-emptively attack and “liberate” the South in its latest outburst against the annual joint military drills by the United States and South Korea. (Photo by Kim Jun-bum/Yonhap via AP Photo)

The “EMIEW3” robot (R) demonstrates communicating with a visitor during a press preview in Tokyo on April 8, 2016. Japanese electronics giant Hitachi unveiled its humanoid customer service and guidance robot “EMIEW3” and “remote brain” robotics IT platform. (Photo by Toshifumi Kitamura/AFP Photo)

The Dynasphere, an electrically-driven wheel, invented by Mr. J. A. Purves of Taunton and his son. It had 2.5 horse power and once attained a speed of 25 mph. (Photo by Fox Photos/Getty Images). 1932

In this March 14, 2015 photo, tourists take pictures from a viewing area at Iguazu Falls in Brazil. From walkways and bridges, viewers can count 270 water falls almost 100 meters (330 feet) high. (Photo by Jorge Saenz/AP Photo)

Tourists walk above a tea plantation in Enshi, Hubei province, December 27, 2015. (Photo by Reuters/Stringer)

An Afghan woman collects cotton buds at governmental farms in Jalalabad, Afghanistan, 20 October 2020. Afghanistan's agriculture and livestock department in Nangarhar province hire women and people in need of cash assistance to harvest cotton from their farms. (Photo by Ghulamullah Habibi/EPA/EFE)

Individuals brave the freezing temparature in Combs reservoir as they take part in a cold water therapy treatment near Chapel en le Frith, northwest England on January 1, 2021. (Photo by Oli Scarff/AFP Photo)

Tourists and locals apply colour dust to each other as they celebrate Holi festival in Kolkata, Eastern India, 28 March 2021. (Photo by Piyal Adhikary/EPA/EFE)