HONG KONG—Four Hong Kong student leaders charged with “advocating terrorism” after their union passed a motion last month mourning the death of a 50-year-old who stabbed a policeman before killing himself were denied bail on Thursday. The four, aged 18–20 and all from the University of Hong Kong (HKU), are the latest democracy activists to be denied bail under a sweeping national security law that Beijing imposed on the former British colony last year. Some student supporters burst into tears as they left West Kowloon Court where Kinson Cheung King-sang, 19, Kwok Wing-ho, 20, Chris Shing-hang Todorovski, 18, and Yung Chung-hei, 19, were denied bail. Magistrate Peter Law initially granted bail to Yung but the decision was immediately appealed by the prosecutors. The case was adjourned to Sept. 14. “I didn’t expect university students to be charged with advocating terrorism. They just issued a statement,” said Jeff, 18, a student …