I could not complete my assignment without the great help and useful advice from my teacher, my family as well as my friends. Firstly, I would like to express my great thanks to y supervisor, . Nguyen Thi Van Lam for her enthusiastic help. Secondly, I would like to express my deep thanks to all the teachers in Foreign Language Department of Vinh University for giving me helpful lectures. My thanks also go to my director, Ms Nguyen Thi Yen and all the colleagues at |