by Li Ho Cheung, William. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 82-88). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgements --- p.vi / Table of Contents --- p.vii / List of Tables --- p.viii / List of Appendices --- p.x / Chapter Chapter 1 : --- Introduction and Literature Review --- p.1 / Chapter Chapter 2 : --- Method --- p.31 / Chapter Chapter 3 : --- Results --- p.48 / Chapter Chapter 4 : --- Discussion --- p.60 / Reference --- p.82 / Appendices --- p.89