People purchase commemorative stamps for the 100 anniversary of the May 4th Movement at Handan branch office of China Post, in Handan City, north China's Hebei Province, May 4, 2019. China Post on Saturday issued a set of two commemorative stamps marking the 100 anniversary of the May Fourth Movement. (Photo: Xinhua)

A stuff member of the Zaozhuang branch office of China Post shows the commemorative stamps for the 100 anniversary of the May 4th Movement, in Zaozhuang City, east China's Shandong Province, May 4, 2019. China Post on Saturday issued a set of two commemorative stamps marking the 100 anniversary of the May Fourth Movement. (Photo: Xinhua)

People purchase commemorative stamps for the 100 anniversary of the May Fourth Movement at Ji'an branch office of China Post in Ji'an City, east China's Jiangxi Province, May 4, 2019. China Post on Saturday issued a set of two commemorative stamps marking the 100 anniversary of the May Fourth Movement. (Photo: Xinhua)