经过三个月的努力研究和撰写，在即将完成论文之前，我在此感谢各位老师的指

Through the efforts of research and writing three months before the paper is nearing completion, I would like to thank all the teachers over to help, and thank my classmates and friends gave me selfless help, but also to support my family quietly express my most sincere thanks.

After three months of hard research and writing, in the near completion of the paper, I would like to thank all the teachers for their guidance, at the same time thank my classmates and friends for my selfless help, but also silently support my family to express my most sincere thanks.

After three months of hard research and writing, before I finish my thesis, I would like to thank all the teachers for their guidance, my classmates and friends for their unselfish help, and my sincere thanks to my family for their silent support.