Four-years-old police dog Dongdong inspects luggages in a train station in Chengdu, Sichuan, on Feb 20, 2013. This year is Dongdong's first year paticipating in the security inspection works during Spring Festival travel rush. Dongdong has to go through multiple trainings before it goes out on duty. Its job is to inspect the train station and passengers' luggages for dangerous items by smelling them.[Photo/Xinhua] 

Four-years-old police dog Dongdong trains with its trainer in a police dog training base in Chengdu, Sichuan, on Feb 20, 2013. This year is Dongdong's first year paticipating in the security inspection works during Spring Festival travel rush. Dongdong has to go through multiple trainings before it goes out on duty. Its job is to inspect the train station and passengers' luggages for dangerous items by smelling them.[Photo/Xinhua]