Fan Wenyi:

The newspaper is going to Fu Zi, but my mood is quite mixed. After three years of graduate school, I have experienced a lot. I have a lovely baby. During the period of feeding the baby independently, I felt the happiness of being a mother for the first time and suffered the hardships of life. However, it also makes my attitude towards life more and more optimistic and stronger. Thank you for the hardships you have gone through in recent years, and thank you for the dribs and drabs in your life and study in recent years. At the moment when you are about to end your student career, I want to express some heartfelt wishes.

During my master's degree with my tutor, Professor Cong Zhijie, Professor Cong has always been very tolerant of students like me and has a lot of shame in his heart. Tutors are very strict in their studies and responsible for students, but for a long time, taking care of children and doing housework has become the theme of my life, and I can't settle down to complete my study tasks according to the guidance of tutors. I sincerely apologize to my mentors.

Thank you for your help during my study. I am deeply moved and encouraged by your suggestions on the topic selection and specific writing of master's degree thesis, and thank them for their encouragement and support for thesis writing. I would like to express my heartfelt thanks here. Thank my family for their silent efforts to me. It is because of their care, support and encouragement that I am confident that I can successfully complete my studies.

Finally, thank you for your valuable comments and suggestions on this paper, which is an opportunity for me to further understand and improve the paper.

Fan Wener:

After writing the paper, I look back and feel a lot. Three years ago, I came to Guangdong Teachers College of Technology with passion and dreams, where I left my academic footprint and witnessed my growth. When I want to say goodbye to all this familiarity, what is most buried in my heart is infinite gratitude.

First of all, I would like to thank my tutor Professor Pan Zimian for successfully completing this paper. Teacher Pan's profound knowledge and rigorous academic attitude have been deeply affecting me. My tutor has given me great help in selecting topics, determining topics, conceiving ideas and writing specific contents. It is under his encouragement and guidance that my graduation thesis can finally be published. During my three-year postgraduate study, Mr. Pan gave me a lot of guidance and help, which taught me how to do things seriously and how to study without hesitation.

I am grateful to Liu, the actor born in 1969, and the teachers Ren Ping, Miao Sulian, Chen Lijun, Li Ning and Yang Sujuan of the College of Education for their careful teaching and care and help in my study and life. It is their hard cultivation that enabled me to successfully complete my studies.

I also want to thank my classmates for their help, care and sharing. The friendship between classmates and roommates will be one of the most unforgettable and precious memories in my life. Thanks to the authors of all references, their achievements have provided a solid foundation for my thesis writing. Thanks to my family, they gave me tolerance, encouragement and support.

These three years of study are full of happiness, but also accompanied by hardships, which is worth cherishing and nostalgia for my life. I hope this paper can draw a satisfactory end for my graduate life. With gratitude, I am about to embark on a new journey, and I will continue to maintain an open-minded attitude towards knowledge and a rigorous attitude towards learning in order to seek self-study.

Fan Wensan:

This research and thesis was completed under the cordial care and careful guidance of the tutor, Associate Professor Jian Zheng. His serious scientific attitude, rigorous academic spirit and work style of Excellence deeply infected and inspired me. From the selection of the subject to the final completion of the project, Mr. Zheng has always given me careful guidance and unremitting support.

For more than two years, Professor Zheng not only gave me careful guidance in my study, but also gave me meticulous care in my thoughts and life. Sincere thanks and high respect to Mr. Zheng.

Here, I would also like to thank all the students in Electrical Building 105 for having a happy postgraduate life together. It is because of your help and support that I can overcome one difficulty after another until I successfully finish this paper. Special thanks to my sister Ye Qiuxiang, who has done a lot of work on this topic and given me a lot of help.

When the paper is about to be completed, my mood can't be calm. How many respectable teachers, classmates and friends gave me wordless help from the beginning to the smooth completion of the thesis? Please accept my sincere thanks! Finally, I want to thank my parents who raised me with great pains. Thank you!