Many people given invaluable supports while I was pursuing this research. This thesis couldnot have been completed without the help of my supervisor, students, friends and family, towhom even words fail to express my gratitude.
First and foremost, I wish to deeply acknowledge my gratitude to Prof. Mrs Zhao, mysupervisor, whose invaluable and thoughtful comments,advice and encouragement helped metremendously throughout this study; without her guidance, this thesis could not have beencompleted successfully in appropriate time. My sincere and deep appreciation also goes to allthe professors and teachers,for their special guidance and helpful advices. Through theircourses I have learned a great deal during the period I stayed in the college.
I would also like to express my sincere thanks to and my classmates and friends who havehelped me a great deal throughout my study. Special thanks go to the students and instructorsworking in the School of Tibetan Language and Culture in Northwest University forNationalities, who voluntarily participated in this survey. Without their supports andcooperation, the present thesis is impossible......