Trainer Han Chaoyang and police dog "Zhui Feng" interact with each other at the Tianjin West Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Wang Ji and police dog "Cha Cha" are on duty on a platform of the Tianjin Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Zhao Hui and police dog "Fen Di" go for a rest at the police dog base of the Tianjin branch of the Beijing railway public security bureau after a training session in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Zhao Hui and police dog "Fen Di" take part in a training session at the police dog base of the Tianjin branch of the Beijing railway public security bureau in north China's Tianjin, Jan. 31, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Han Chaoyang and police dog "Zhui Feng" patrol at the Tianjin West Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Wang Ji and police dog "Cha Cha" patrol at the waiting hall of the Tianjin Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Wang Ji and police dog "Cha Cha" are on duty on a platform of the Tianjin Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Wang Ji and police dog "Cha Cha" interact with each other during a rest on the square of the Tianjin Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Trainer Han Chaoyang and police dog "Zhui Feng" check the luggage of passengers at a railway station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)

Policemen and police dogs patrol on the square of the Tianjin Railway Station in north China's Tianjin, Feb. 1, 2021. "Fen Di", a German Dutch hybrid dog and also a guard dog at the Tianjin branch of the Beijing railway public security bureau, has been working and living with its trainer Zhao Hui for three years. (Xinhua/Zhao Zishuo)