WHAT has been the ''irritant'' to the stability of Hong Kong over the past 13 months? Answer: the Sino-British talks. And what has been the concern of every Hong Kong citizen over the past 12 months? Answer: the Sino-British talks. What broke the hearts of Hong Kong residents last month? Answer: the termination of the Sino-British talks. Having recognised the impact of these talks on the future of Hong Kong and with sponsorship coming from Oxford University Press, students from Diocesan Boys' School, Heep Yunn School, Queen's College, St Francis' Canossian College and Kowloon Wah Yan College are to hold a forum entitled ''Challenges Facing Hong Kong's Economy'' on Saturday. It is aimed at investigating the causes of the dispute and forecasting its possible socio-economic effects on the future of Hong Kong. Participants will be given an opportunity to voice their opinions on the topic so as to promote public discussion of current issues among the young. Prominent speakers will include Professor Cheung Ng-sheung (head of the Department of Economics at the University of Hong Kong), Dr Ho Lok-sang (lecturer at the Department of Economics, Chinese University of Hong Kong) and Dr Law Cheung-kwok (director ofSouth China Research). Mr C.C. Choi, former chief examiner of HKCEE Economics, will provide the commentary throughout the forum with his expertise in the field of economics. The forum will be held at Heep Yunn School from 10 am to 12.30 pm. Admission is free. Interested students should contact any of the following: Wong Wai-ho (761-9105), Ng Chi-fai (321-2621) or Philip Kwok (715-4547). Wai-ho is chairman of DBS Business Studies Club