... ...............................................................................................................................41iiiACKNOWLEDGEMENTSFirst of all, I would like to express my deep gratitude to all my teachers at College of Foreign Languages, Vietnam National University-Hanoi for their valuable lectures. And their knowledge, their ... correction.I would like to acknowledge my debt to Assoc. Prof. Dr. Lê Hùng Tiến and the staff members of Postgraduate Department, College of Foreign Languages, VNU-Hanoi for their enthusiastic support.I ... helped me during the period of my study at College of Foreign Languages, VNU-Hanoi.Finally, I wish to thank my wife for the love she gives me and her encouragement in my doing this thesis. ...