Fan Wenyi

Time flies, in a blink of an eye, two and a half years of postgraduate study has come to an end, and the thesis is about to enter the defense stage. In the whole writing process of the thesis, in addition to my own efforts, I can't do without the guidance of teachers, the help of my classmates and the support of my family.

First of all, I would like to express my heartfelt thanks to my tutor Professor Zhang Dan. Her meticulous, meticulous and conscientious work style is an example for me to learn, which deeply infects and inspires me. The choice of research direction, the determination of the topic of the paper, the formation of the framework structure, the writing of the paper, the repeated revision and finalization of the paper have all been carefully guided by Mr. Zhang. Every time Teacher Zhang teaches me, it is an education and improvement for me. Sincere thanks and high respect to the teacher. At the same time, I also want to thank all the other teachers who taught me knowledge and the truth of being a man. It was their teaching that made me gain a lot in the learning process and greatly expanded my knowledge. In addition, I would also like to thank all the students who have spent their study life together. It was their help and concern that enriched and enriched my learning experience.

Finally, I want to thank my family for their support. Their support has always been my motivation.

Although the writing of this paper has come to an end, I still feel a lot of regrets. Due to the limitation of my professional level and energy, there are still many shortcomings in this paper. I urge all experts and scholars to criticize and correct me. The master's study is almost over, but the study is not over yet, and there is still a long way to go. I will keep moving forward and strive for greater progress.

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Fan wener

After a year of hard work, my graduation thesis finally came to an end. While feeling gratified, I would like to express my gratitude to the teachers, experts, scholars and classmates who have helped me and supported me.

First of all, I would like to thank my mentor from the bottom of my heart? -Professor, from the topic selection and conception to the final paper, I have devoted a lot of efforts to my tutor. -The teacher's rigorous academic attitude and noble and peaceful manner have benefited me a lot.

In the thesis writing project, I consulted many valuable documents, and I would like to express my gratitude to these experts and scholars! They have done a lot of preliminary work and research in this field, which has given me a lot of inspiration, increased my knowledge and broadened my thinking.

Secondly, I also want to thank the students who helped me! They gave me a lot of help in the process of writing my thesis, and their opinions and suggestions inspired me a lot.

In addition, thanks to the experts who reviewed my thesis in advance! Due to my limited time, energy and ability, I still have many regrets about the fields involved in this paper. Your criticism and suggestions will be my motivation to continue my study.

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