AcknowledgementThanks for giving me this chance to write this paper and make a perfect conclusion of my four years university life
By the writing of this paper, I realize I have gained more than I can imagine and have a relatively wonderful colleage life
I would like to thank you and those who have offered a great help in my writing of the thesis
Cetainly, my deepest gratitude goes first and foremost to my supervisor Ms
Shi Junhui, for her constant encouragement and guidance
Her guidance in correction and suggestion on my thesis help me make a big progress through my writing
Without her instruction, the thesis couldn’t have reached this present form
Besides, I also want to show my appreciation and thanks to other teachers and classmates who have given me the great help in my four year