Paramilitary policemen take part in a summer training in Shenzhen, Guangdong province, China, June 27, 2016. (Photo by Reuters/China Daily)

Armed Yemeni children sit in the back of a pick up truck with fighters loyal to Yemen's Saudi-backed President Abedrabbo Mansour Hadi in the Dar saad neighbourhood of the southern Yemeni city of Aden on May 10, 2015, as they continue to battle Shiite Huthi rebels. (Photo by Saleh Al-Obeidi/AFP Photo)

People watch participants, whose faces are painted as popular Mexican figure “Catrina”, during the annual Catrina Fest, part of Day of the Dead celebrations, in Mexico City, Mexico, November 2, 2016. (Photo by Edgard Garrido/Reuters)

A worker unloads fish from a taxi boot at a fish market in Kolkata, India on February 5, 2018. (Photo by Rupak De Chowdhuri/Reuters)

Spanish soldiers of the 7th Airborne Light Infantry Brigade “Galicia” fire a howitzer Light Gun L118 during maneuvers with other units in preparation to NATO's Very High Readiness Joint Task Force (VJTF) in Zaragoza, Spain, April 19, 2016. (Photo by Javier Cebollada/EPA)

A protestor gestures toward the White House on the Ellipse near the South Lawn of the White House during the Women's March on Washington January 21, 2017 in Washington, DC. Large crowds are attending the anti-Trump rally a day after U.S. President Donald Trump was sworn in as the 45th U.S. president. (Photo by Drew Angerer/Getty Images)

A truck is seen in a hole after part of the structure of a bridge collapsed into a river in Changchun, Jilin province May 29, 2011. Two truck passengers were injured, while the cause of the accident is still under investigation, local media reported. (Photo by Reuters/China Daily)

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)