I am deeply indebted to many for providing me incentive and support during the
time that I was witting this graduation paper. First of all, I would like to express
my affectionate and sincere gratitude to my supervisor Mrs Tran Thi Ngoc Lien
(MA) for her valuable suggestion, advice, various materials, comments and
correction. Without her thorough help, this paper would still far from finished.
I would also like to thank all the teachers of Department of Foreign language
who whole- heartedly taught me for the past four years