A firefighter rests next to fire combat truck during a wildfire at Penela, Coimbra, central Portugal, on June 18, 2017. A wildfire in central Portugal killed at least 25 people and injured 16 others, most of them burning to death in their cars, the government said on June 18, 2017. Several hundred firefighters and 160 vehicles were dispatched late on June 17 to tackle the blaze, which broke out in the afternoon in the municipality of Pedrogao Grande before spreading fast across several fronts. (Photo by Patricia De Melo Moreira/AFP Photo)

Chinese soldiers leave after Chinese President Xi Jinping inspected troops of People's Liberation Army (PLA) Hong Kong Garrison at the Shek Kong Barracks in Hong Kong, Friday, June 30, 2017. Xi landed in Hong Kong Thursday to mark the 20th anniversary of Beijing taking control of the former British colony, accompanied by a formidable layer of security as authorities showed little patience for pro-democracy protests. (Photo by Kin Cheung/AP Photo)

A student aims a stick of wood at Bolivarian National Police officers during clashes outside the Central University in Caracas, Venezuela, Thursday, June 9, 2016. Students had planned to march from Venezuela's top university to elections headquarters, but hundreds of police in riot gear blocked the way. Students covered their faces with Venezuelan flags and threw bottles, stones and sticks while police lobbed tear gas. (Photo by Fernando Llano/AP Photo)

A Filipino girl is carried along a flooded road in suburban Mandaluyong, east of Manila, Philippines, as monsoon downpours intensify while Typhoon Nepartak exits the country on Friday, July 8, 2016. In the Philippine capital, Manila, and outlying provinces, classes in many schools were suspended and at least six flights, including one scheduled to come from Taiwan, were canceled because of stormy weather and floods following monsoon downpours intensified by the typhoon, Filipino officials said. (Photo by Aaron Favila/AP Photo)

A man poses for a photograph in front of a mural of Democrat US presidential nominee Hillary Clinton clad in a swimsuit bearing the colours of the US flag in West Footscray in Melbourne on July 30, 2016. An Australian mural of US presidential nominee Hillary Clinton in a revealing, stars and stripes swimsuit may be taken down, after it has reportedly been deemed offensive. (Photo by Paul Crock/AFP Photo)

A nun checks her mobile phone as she lies near a victim laid on a ladder following an earthquake in Amatrice Italy, Wednesday, August 24, 2016. The magnitude 6 quake struck at 3:36 a.m. (01:36 GMT) and was felt across a broad swath of central Italy, including Rome where residents of the capital felt a long swaying followed by aftershocks. (Photo by Massimo Percossi/ANSA via AP Photo)

A combination photo shows various popular street foods under $6 from various hawker food stalls and eateries in Singapore, taken between July 28 to 31, 2016. Top row (L to R) bak chor mee, soya sauce chicken; Middle row (L to R) laksa, hokkien mee, nasi lemak, ice kachang; Bottom row (L to R) rojak, roti prata and satay. (Photo by Edgar Su/Reuters)

One-year-old female giant panda cub Nuan Nuan reacts inside her enclosure during joint birthday celebrations for the panda and its ten-year-old mother Liang Liang at the National Zoo in Kuala Lumpur on August 23, 2016. Giant pandas Liang Liang, aged 10, and her Malaysian-born cub Nuan Nuan, 1, were born on August 23, 2006 and August 18, 2015 respectivetly. (Photo by Mohd Rasfan/AFP Photo)