Promotional models use their smartphones during their break at the Global Mobile Internet Conference in Beijing May 6, 2014. Mobile Internet industry executives, developers and investors from more than 30 countries took part in the Global Mobile Internet Conference in Beijing, the organiser said. (Photo by Kim Kyung-Hoon/Reuters)

A Puffin jumps into its burrow with a mouthful of sea eels to feed its chick on Skomer Island, Pembrokeshire in Wales, Britain June 21, 2016. (Photo by Rebecca Naden/Reuters)

A woman plays around as she walks across a glass-bottomed suspension bridge in a scenic zone in Pingjiang county in southern China's Hunan province Thursday, September 24, 2015. The bridge, 300 meters (984 feet) long and 180 meters (590 feet), opened to visitors on Thursday for the first time since its conversion from a regular suspension bridge was completed. (Photo by Chinatopix Via AP Photo)

A protestor performs outside the parliament during a demonstration against austerity measures announced by the Spanish government in Madrid, Spain on September 29, 2012. (Photo by Andres Kudacki/Associated Press)

This photo taken on February 26, 2019 shows an aerial view of a tea field in Zhangping in China's eastern Fujian province. (Photo by AFP Photo/China Stringer Network)

A photo taken on August 21, 2017 shows girls passing in front of a building with a display of the Soviet state founder Vladimir Lenin Order in Volgograd, Russia. Volgograd Arena will host several cames of the FIFA World Cup 2018. (Photo by Mladen Antonov/AFP Photo)

A moon light illuminates the sky through the clouds over a large line of grass between some home houses in the small village of Tafalla, northern Spain, Tuesday, May 1, 2018. (Photo by Alvaro Barrientos/AP Photo)

Ministry of Defence handout photo of Chinooks from RAF Odiham as they take part in the Royal Air Force flypast over central London to mark the centenary of the RAF on Tuesday, July 10, 2018. (Photo by SAC Pippa Fowles (RAF)/PA Wire)