Let me give you a well-written example: there is a bright future in another village, and clear water is flowing. How much wind and rain, how much joy. Inadvertently, with a flick of a finger, it seems like water has passed. Looking back, my eyes stayed between the lines, but my thoughts walked through the beautiful campus. The sun and the moon were not flooded, and the spring and autumn were orderly. Everything here is about to change, and I can't help feeling deeply and want to cry. Looking back on these three years, although I can't talk about achievements, I cherish them. Three years passed inadvertently, leaving me with endless gratitude to teachers, classmates, friends and relatives. Professor Shilin is a respected teacher with profound knowledge and extraordinary wisdom. His words and deeds gave me great encouragement and help. Pale language can't express my inner gratitude: from professional study to research methods, from scientific research and creation to thesis guidance, from trivial matters of life to job hunting, learning, doing things, being a man and respecting teachers are the navigation marks of my life everywhere. Students will never forget their tireless teaching and encouragement, rigorous academic attitude and innate intellectual self-restraint, which is also my motivation to keep moving forward. The writing of this thesis has been carefully and comprehensively guided by respecting teachers, and students know that they are only knowledgeable and shallow, and they only want this and have not failed their teachers. In fact, there are still many people to thank, many, how to say "thank you"? Teacher Zhao Hui, Teacher Roman, Teacher Fang Hongmei, Teacher Tu Bo, Teacher Bai Lingjie ... Your earnest teaching, preaching, dispelling doubts and encouraging support have made me unforgettable; Ding Jing, Zhao Hui, Wang Ying, Wang Hongyan, Pan Liangzhi ... Students, over the past three years, it was your selfless help and fighting side by side that made me deeply feel the warmth and happiness of the collective surrounded by friendship; Half a hundred parents have worked tirelessly to protect themselves for more than 20 years. The kindness of parents is beyond words. My daughter will be here to thank you and repay you. Classmates have been in love for three years. Long Deyong, a fellow traveler, died of illness two months ago, and his heart was filled with infinite grief. He must be in heaven, and he will be happy to see our achievements. Ending one journey is to start another. Life is like a trip, it doesn't care about the purpose of the trip, only about the scenery along the way and the mood of watching it. I will continue to work hard and enjoy the scenery along the way. At this point, the heart did not stop beating. ...