Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

Artists perform during the opening show directed by German director Volker Hesse, on the opening day of the Gotthard rail tunnel, at the fairground Rynaecht at the northern portal in Erstfeld, Switzerland, Wednesday, June 1, 2016. The construction of the 57 kilometer long tunnel began in 1999, the breakthrough was in 2010. After the official opening on June 1, the commercial operation will start in December 2016. (Photo by Ruben Sprich\Pool Photo via AP Photo)

Attendees look at Volkswagen's BUDD-e, a long distance electric vehicle, displayed during a press event at CES 2016 at The Chelsea at The Cosmopolitan of Las Vegas on January 5, 2016 in Las Vegas, Nevada. CES, the world's largest annual consumer technology trade show, runs from January 6-9 and is expected to feature 3,600 exhibitors showing off their latest products and services to more than 150,000 attendees. (Photo by David Becker/Getty Images)

Elephants feast on fruits and vegetables during the elephant buffet prior to the start of the 2016 King's Cup Elephant Polo event in Bangkok, Thailand, 10 March 2016. The annual charity event, now in its 14th edition, runs until 13 March and will involve 18 elephants brought from tourist trekking camps in Pattaya as well as some unemployed in Surin. A total of 10 teams encompassing over 40 players will take part in the event directed at raising funds to improve the lives of elephants and elephant conservation. (Photo by Diego Azubel/EPA)

A handout picture provided by the press service of MORTON Group of Companies, show the balloon of Russian adventurer Fedor Konyukhov in the sky during his solo round-the-world balloon flight just after taking off from a spot near Northam, 96 kilometres north-east of Perth in Western Australia, 12 July 2016. Fedor Konyukhov took off from Northam on 12 July 2016 in attempt to beat the record of 13 days of American aviator Steve Fossett. (Photo by EPA/Morton Press Service)

A flight crew from China Airlines, wearing protective masks, stand in the international terminal after arriving on a flight from Taipei at Los Angeles International Airport (LAX) on February 28, 2020 in Los Angeles, California. The World Health Organization (WHO) has raised the global coronavirus risk level to “very high”. (Photo by Mario Tama/Getty Images)

Shaolin boys practice kung fu in the sweltering heat during the zen shaolin music ceremony at shaolin temple, Dengfeng, Henan province, China on August 4, 2019. Shaolin unique skills include: shaolin arhat formation, three gun sashimi, shaolin stick, shaolin stone lock skill, iron hand splitting bricks, water training, fist and foot sparring. (Photo by Sipa Asia/Rex Features/Shutterstock)

Performers on boats take part in the Qintong Boat Festival at Qin Lake National Wetland Park on April 6, 2019 in Taizhou, Jiangsu Province of China. The boat festival is held around the Qingming Festival every year, and up to 10,000 participants from nearby villages and towns, with more than 500 boats, took part in the event this year. (Photo by Tang Dehong/VCG via Getty Images)