Police dog "Long Ya" checks train K112 with its trainer Ren Wei at Guiyang Railway Station in Guiyang, capital of southwest China's Guizhou Province, Feb. 16, 2018. The 7-year-old police dog "Long Ya" has been in service for over 6 years. The period of the Spring Festival travel rush is the busiest time for "Long Ya" in a year. (Xinhua/Ou Dongqu)