Trainers from Tianjiao Special Guard/Security Consultant Ltd. Co. engage trainees dressed in swimming suits as they crawl on the beach during a training session in Sanya, Hainan province January 8, 2012. (Photo by CHINA DAILY/Reuters)

A boy holds his mother's leg as he cries in front of their damaged house after a strong 6.6 magnitude earthquake at Longmen village, Lushan county in Ya'an, Sichuan province. (Photo by Jason Lee/Reuters)

A man from Dinka tribe holds his AK-47 rifle in front of cows in a Dinka cattle herders camp near Rumbek, capital of the Lakes State in central South Sudan December 14, 2013. (Photo by Goran Tomasevic/Reuters)

A model poses beside a Renault DeZir concept car during the media day of the Shanghai International Automobile Industry Exhibition at Shanghai New International Expo Center on April 20, 2011 in Shanghai, China. The 14th Shanghai International Automobile Industry Exhibition (Auto Shanghai 2011) will be held from April 21 to 28 with the theme of “Innovation For Tomorrow”. About 2,000 carmakers and parts providers from 20 countries are due to showcase 1,100 car models, 75 of which makes their world premieres in the auto show. (Photo by Feng Li/Getty Images)

A Russian trenchmortar crew run to take up a new firing position in the Stalingrad area during the Great Patriotic War. (Photo by Keystone/Getty Images). October 1942

The Last Bell (we mean the bell that informs the pupils about the beginning or the ending of the lessons) is the traditional feast of the Russian pupils who leave the school. The Last School Bell feast occurs in the end of May, when the school year has already finished, but the final examinations have not begun yet. Luhansk (also known as Lugansk – a city in southeastern Ukraine), 2010. (Photo by X-F@ctor's bloG)

Two women lighting cigarettes on a tennis court in Essex, England circa 1930's. (Photo by Keystone View/FPG/Getty Images)

Naturally, it is important that a baby learn the right habits. This woman demonstrates that smoking is wrong for babies. From a series of images parodying women's lifestyle and beauty magazines. (Photo by Jacobsen/Getty Images). 1955