A pro-democracy demonstrator fights with a Soviet soldier on top of a tank parked in front of the Russian Federation building on August 19, 1991, after a coup toppled Soviet President Mikhail Gorbachev. The same day, thousands in Moscow, Leningrad, and other cities answered Russian Republic President Boris Yeltsin's call to raise barricades against tanks and troops. (Dima Tanin/AFP/Getty Images)

This Thursday, January 22, 2015 photo made with a long exposure shows the glow from a Noctiluca scintillans algal bloom along the seashore in Hong Kong. The luminescence, also called Sea Sparkle, is triggered by farm pollution that can be devastating to marine life and local fisheries, according to University of Georgia oceanographer Samantha Joye. Noctiluca itself does not produce neurotoxins like other similar organisms do. But its role as both prey and predator tends can eventually magnify the accumulation of toxins in the food chain, according to R. Eugene Turner at Louisiana State University. (Photo by Kin Cheung/AP Photo)

People try to get a roast chicken at the first Costco outlet in China, on the stores opening day in Shanghai on August 27, 2019. China has proved a brutal battleground for overseas food retailers in recent years, with many failing to understand consumer habits and tastes as well as local competitors building a stronger presence. (Photo by Hector Retamal/AFP Photo)

A participant in wingsuit flies above Tianmen Mountain at Zhangjiajie Scenic Spot during the 4th Red Bull WWL China Grand Prix on October 16, 2015 in Zhangjiajie, Hunan Province of China. The 4th Red Bull WWL China Grand Prix will last three days from October 16-18 in Zhangjiajie. (Photo by ChinaFotoPress/Getty Images)

Arizona Cardinals cheerleader Claire Thorton, center, smiles as Air Force Capt. Eric Straub proposes to her during the first half of an NFL football game against the Washington Redskins, Sunday, October 12, 2014, in Glendale, Ariz. Thorton accepted the proposal. (Photo by Rick Scuteri/AP Photo)

Li Yuming, a local farmer who is interested in scientific invention, works on his unfinished miniature submarine “Xiaguang V” on the outskirts of Wuhan, capital of central China's Hubei province August 24, 2007. “Xiaguang V”, which is 3-metre long, 1.2-metre in height, has a maximum diving depth of 20 metres, and can hold two adults and one child at the same time. The submarine will be used for tour after safety test, local media said. (Photo by Reuters/Stringer)

An explosion at a petrochemical plant is seen in Rizhao, Shandong province, July 16, 2015. According to Xinhua News Agency, a fire broke out after the explosion, which was caused by a liquified hydrocarbon leak at the plant, on Thursday morning. There was no report of casualties yet. (Photo by Reuters/China Daily)

A bride gets her make-up done before the start of a mass marriage ceremony in Kolkata, India, February 14, 2016. A total of 150 tribal Hindu, Muslim and Christian couples from various villages across the state took their wedding vows on Sunday during the day-long mass marriage ceremony organised by a social organisation, the organisers said. (Photo by Rupak De Chowdhuri/Reuters)