1. Prologue: Good afternoon, teachers! My name is xxx, and I am a student in Class X, Grade xx. My thesis topic is xxx, which was completed under the careful guidance of xx tutor.

Here, I would like to express my deep gratitude to my tutor, to all the teachers who have taken pains to participate in my thesis defense, and to express my heartfelt respect to all the teachers who have had the opportunity to listen to my teachings in the past four years. Next, I will report the design purpose and main contents of this paper to all teachers, and ask them to criticize and guide me.

2. Conclusion: The writing of this paper makes me more and more aware of the process of my lack of knowledge and experience. Although I try my best to collect information, do experiments and write papers with what I have learned, the measured data are incomplete and many things are still half-understood. There are still many shortcomings in the paper, which need to be improved. Please criticize and correct me a lot, so that I can learn more in my future study! thank you