签字日期: 年月日签字日期: 年月日 Acknowledgments I am honored to have the occasion to express my thanks to the people who have helped and supported me during pletion of the thesis. First, I wish to give my sincere appreciation and gratitude to my supervisor-professor Chen Chunsheng, without whose help the thesis would not have pleted. Professor Chen not only provided me invaluable suggestions and constructive directions with his profound knowledge in literature and rich research experience during the process of writing this thesis,but also offered me constant encouragement, patient support and heartening care in both my academic and daily life all my years in GNNU. His kindness and patience are highly appreciated and his rigorous scholarship and enthusiasm will influence my life. I also want to give my thanks to the professors and teachers of English Department. Their excellent teaching has imparted a wide range of knowledge to me and laid solid foundation fo