致谢首先要感谢我的指导老师，在论文的写作研究上要求十分严谨。我由衷的感

Acknowledgements <br>First of all, I would like to thank my instructor for his rigorous research on thesis writing. I sincerely thank the teacher for the instructive guidance and spur during the writing of the thesis, especially the revision of the thesis again and again, all of whom can tirelessly give valuable comments and amendments. Only after the teacher’s patient tolerance and careful guidance My paper is produced smoothly, and I would like to express my most sincere thanks. Thanks to all my classmates for making my life richer and more splendid. <br>Finally, thanks to my family, for your tolerance and dedication, so that I can successfully complete my studies and realize my dreams. Only give this monograph to those who have accompanied me and encouraged me, and share my glory together.

Thanks<br>First of all, i would like to thank my instructor, in the writing of the thesis research requirements are very strict. I sincerely thank the teacher in the process of writing the paper with the pain of guidance and encouragement, especially again and again, the paper revision, can take pains to give valuable advice and corrections, in the teacher's patient tolerance and careful guidance, in order to let my paper produce smoothly, in this offer the most sincere thanks. Thanks to all my friends, let my life more rich and brilliant.<br>Finally, thank my family, thank you for your tolerance and dedication, so that I can successfully complete my studies and realize my dream. Only dedicate this paper to those who have been with me and encouraged me, and share my glory together.

thank<br>First of all, I would like to thank my tutor, who is very strict in the research of thesis writing. I sincerely thank the teachers for their painstaking guidance and encouragement in the process of writing the thesis, especially for the revision of the thesis again and again, which can spare no effort to give valuable advice and revision. Only under the patient tolerance and careful guidance of the teachers, can my thesis be successfully produced. I would like to offer my most sincere thanks. Thank all my classmates and friends for making my life more colorful.<br>Finally, thank my family, thank you for your tolerance and dedication, so that I can successfully complete my studies and realize my dream. Only dedicate this paper to those who have accompanied me and encouraged me, and share my glory together.