File photo taken in Feb. 2020 shows Cao Ziyang (R), a high-speed train conductor, works as a volunteer in his community. Working as a conductor of high-speed trains in Jinan section, Cao has been fighting against the COVID-19 epidemic since its beginning. He delivered epidemic prevention supplies to Wuhan many times in 2020, and has been working as volunteer in the community he lives in. (Xinhua)