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 woman walks behind the installation “Wandering boy is forever attractive” (1985) by Tetsumi Kudo during the press preview at the exhibition “Tetsumi Kudo – Retrospective” in the Fridericianum in Kassel, Germany, Friday, September 23, 2016. The exhibition offers an in-depth, comprehensive view of works by the Japanese artist Kudo. It starts on Sept. 25, 2016 and lasts until Jan. 1, 2017. (Photo by Jens Meyer/AP Photo)

Friends of Li Guojun drive a homemade tank-shaped vehicle in Kangping county, China. Li, a farmer who is a fan of tanks, spent six months with help from his friends to construct the almost 20-foot vehicle which weighs 2.5 tons. (Photo by Sheng Li/Reuters)

Members of the New People's Army (NPA) female guerrillas perform a cultural show during the release of a Philippines army soldier in Sugbongcogon town, Misamis Oriental, southern Philippines, November 20, 2015. NPA spokesperson Allan Juanito warned that they will seize more soldiers to exchange them with the government as "Prisoners of war". (Photo by Froilan Gallardo/Reuters)

A woman waters the plants outside her house in an alley at a slum in Mumbai October 28, 2014. (Photo by Danish Siddiqui/Reuters)

A colorful sky at sunset over the snowy mountains in Immenstadt, Bavaria, Germany, 20 November 2014. Cloudy weather is forecast in the region on 21 November. (Photo by Karl-Josef Hildenbrand/EPA)

A climber walks on the ridge beneath the eastern peak of the Gamsberg (2385 meters above sea level) near Grabs, Switzerland, Friday, October 3, 2014. (Photo by Gian Ehrenzeller/AP Photo/Keystone)

A model's make up picture is stuck to a mirror backstage during the Autumn/Winter Madrid's Mercedes Benz Fashion Week, in Madrid, Wednesday, February 1, 2012. (Photo by Daniel Ochoa de Olza/AP Photo)