THE youngest member of a gang which subjected a 15-year-old boy to a six-hour torture was sent to a drug addiction treatment centre by the District Court yesterday. Before passing sentence on Chan Kin-kwok, now 14, Judge Chua said Chan's heroin addiction had deprived him of the two most valuable things in the world - liberty and health. ''We all care about 1997 and we all care about our liberty. But what is more important is our health,'' Judge Chua said. While urging Chan to get rid of his drug habit and to make himself proud of his life, Judge Chua showed him a photograph of a 40-year-old drug addict. She also urged Chan's parents to spend more time with him. Chan, 13 at the time of the offences, was found guilty after trial of false imprisonment and wounding Wong Chiu-wah with intent. His counsel Juliana Chow claimed Chan did not physically take part in the torture. The court heard Chiu-wah was arrested by police for a drug offence, and allegedly revealed the whereabouts of heroin owned by the triad ''big brother'' of a gang. In retaliation for the alleged betrayal, he was tortured by the gang.