At the front line of the war against drugs in Shenzhen, south China's Guangdong Province, a special army - the detachment of sniffer dogs - plays an irreplaceable role. With incredible sense of smell, sniffer dogs have made unusual contribution to the anti-drug criminal investigations and the security work of big events, such as the 2010 Guangzhou Asian Games and 2011 Shenzhen World University Games. (vip.people.com.cn/Liao Jian)