Pete McLeod of Canada flies in formation with Nigel Lamb of Great Britain, Martin Sonka of the Czech Republic and Kirby Chambliss of the United States during a Recon flight prior to the seventh stage of the Red Bull Air Race World Championship over the Hoover Dam on October 09, 2014 on the border between the U.S. states of Arizona and Nevada. (Photo by Joerg Mitter/Red Bull via Getty Images)

“Freedom”. After the 30 years banning import large motorcycle, in 2007, the Taiwan government reopened the import licensing of the motorcycle displacement over 550 cubic centimeter. Those large bikes, which were never seen before, were strange thought and treated unequally frequently. However, those adversity will not stop those enthusiastic bike riders from chasing the road of freedom. Photo location: Taiwan. (Photo and caption by 火花 羅/National Geographic Photo Contest)

A boy crawls under a cow during a religious ceremony celebrating the Tihar festival, also called Diwali, in Kathmandu, October 23, 2014. Hindus all over Nepal are celebrating the festival during which they worship cows, which are considered a maternal figure, and other animals. Also known as the festival of lights, devotees worship the goddess of wealth Laxmi by illuminating and decorating their homes using garlands, oil lamps, candles and colourful light bulbs. (Photo by Navesh Chitrakar/Reuters)

Chinese aids activists hand out condoms in a subway train in Wuhan, central China's Hubei province on December 1, 2014. The World Health Organization issued a call to action to China on December 1, 2014 over HIV/AIDS as government figures said nearly half a million people are living with the disease or its precursor, with hundreds of thousands more thought to be undiagnosed. (Photo by AFP Photo)

Tourists take a “selfie” as demonstrators burn a trash container during a May Day rally in Barcelona, Spain, on May 1, 2014. Tens of thousands of workers marked May Day in European cities with a mix of anger and gloom over austerity measures imposed by leaders trying to contain the eurozone's intractable debt crisis. (Photo by Manu Fernandez/Associated Press)

This picture taken on July 15, 2014 shows a bridge submerged in floodwaters in the ancient town of Fenghuang, central China's Hunan province. Rainstorms lashed central China's Hunan Province and southwest China's Guizhou Province, affecting over 1 million people and flooding a historical town, state media reported. (Photo by AFP Photo)

Two dancers pass each other as they compete in a heat during the All Scotland Championships in Irish Dancing at the Royal Concert Hall in Glasgow, Scotland. The championships attract over 2000 dancers from more than 300 dance schools, from countires such as North America, South Africa, Australia and Russia. (Photo by David Moir/Reuters)

View of colourful rock formations at the Zhangye Danxia Landform Geological Park in Gansu Province, China. The Zhangye Danxia Landform Geological Park is 40km from Zhangye city. The park spans more than 400 square kilometers in Gansu. The unusual terrain is the result of red sandstone and mineral deposits carved over the years by natural forces. (Photo by ImagineChina/The Grosby Group)