Students attend a stewardess skill training for the upcoming 2017 entrance examination for art majors in colleges in Luoyang, central China's Henan Province, January 4, 2017. Along with how to stand, how to sit is also covered in these classes. (Photo by Li Bo/Xinhua/Barcroft Images)

Athletes attend training session at the Ak Bulak Nordic Arena outside Almaty, Kazakhstan, July 16, 2015. Kazakhstan is aspiring to host the 2022 Winter Olympics but many in the Central Asian nation view the bid as yet another vanity project of long-ruling President Nursultan Nazarbayev. Almaty, the financial capital, will go head-to-head with the Chinese metropolis Beijing on Friday when the International Olympic Committee elects the winner at its session in Malaysia. (Photo by Shamil Zhumatov/Reuters)

The new EVR system which allows the recording of television programmes which can then be watched at the owner's discretion. The new Teleplayer has been produced in partnership with Rank Bush Murphy Ltd and EVR and has enormous potential. 21st September 1970. (Photo by Central Press/Getty Images)

A Toyota i-Road electric vehicle drives in a underground parking lot in Tokyo April 9, 2015. Tokyoites will get a chance to zip around town on Toyota Motor Corp's three-wheeled electric car-cum-motorbike from Friday, in a trial aimed at crafting a global business model to reduce gridlock and pollution. (Photo by Thomas Peter/Reuters)

Cosplayer Leah Panos as Snow White donates blood at San Diego Blood Bank on July 25, 2020 in San Diego, California. With the cancellation of 2020 Comic-Con International due to the coronavirus pandemic, the San Diego Blood Bank moved their 44th Annual Comic-Con's Robert A. Heinlein Blood Drive to encompass all of their locations and mobile units. (Photo by Daniel Knighton/Getty Images)

Caroline Wozniacki of Denmark serves to Alisa Kleybanova of Russia during the BNP Paribas Open at the Indian Wells Tennis Garden on March 15, 2011 in Indian Wells, California. (Photo by Matthew Stockman/Getty Images)

Small transportation boats, known as bumboats, leave trails of light as they travel across Marina Bay past the skyline of Singapore in this photo taken in 2004. Singapore holds a Jubilee weekend from 7 to 10 August to celebrate the 50th anniversary of its independence. Fifty years ago, hundreds of small boats lined the Singapore river in the city centre. Today, most small boats are gone, except a handful of neon-lit tourist ferries. Maritime trade is still the backbone of the city-state but after decades of rapid growth Singapore, which at less than half the size of London is among the world’s most densely populated nations, is also a popular tourist destination and a thriving global financial hub. (Photo by Edgar Su/Reuters)

Bonbibi, Treehouse Point, Fall City, WA. The Bonbibi is balanced on two steel yokes. The yokes spread out the load and allow for tree growth and movement in the wind. A small deck hangs from the beams below and uses the treehouse itself to shelter guests. (Photo by Pete Nelson)