To get young people interested in films, the Urban Council, organiser of the 21st Hong Kong International Film Festival, will hold three free movie previews especially for secondary and tertiary students today and tomorrow at the Ko Shan Theatre. Guests from film-related fields and three festival programmers will share their views and hold discussions with the audiences after each screening. Only ticket-holders will be let in. Those interested should telephone the festivals office at 2734 2908 or fax 2366 5206 to reserve tickets. The schedule of the previews is: Hiroshima 28 (1974/HK/100 minutes) - today at 5 pm; Betrayal (1996/HK/32 minutes) and Neon Goddesses (1996/HK/46 minutes) - tomorrow at noon; Gabbeh (1996/Iran/69 minutes) - tomorrow at 5 pm. Directed by Lung Kong and starring Josephine Siao, Hiroshima 28 deals with the second-generation victims of the nuclear holocaust at the Japanese city. The Grand Prize winner at the Hong Kong Independent Short Film and Video Awards 1996, Neon Goddesses and Betrayal will give audiences a chance to see the development of local independent film-making. The Iranian film Gabbeh, with colour, movement and music, is a poetic movie about nomads' lives and dreams.