Thank you for your graduation thesis, which has experienced joy, noise, pain and hesitation from topic selection to data collection and from writing to repeated revision. My mood is so complicated in the process of writing the thesis. Now that I have the final draft of this graduation thesis, my complicated feelings have vanished, and I even have a little sense of accomplishment. It was like being at a grand awards party. I watched others take the stage one after another to receive the prize, but I never got my name. After a long time, a guest finally called my name. At this time, I forgot the long and boring waiting time, walked on the stage happily, and then couldn't wait to express my feelings and express my feelings. This graduation thesis is my stage, and the following words are sincere thanks and feelings expressed on the stage after a little sense of accomplishment: I want to thank my mentor and teacher. She is easy-going and enthusiastic, and she is serious in her studies. In small talk, she can always encourage you like a confidant, and she will always be strict with you on the writing and wording of the paper with "professional standards". From the beginning of the topic selection, the determination of the topic selection, to the repeated revision and polishing of the final paper, xu teacher has been giving me profound and meticulous guidance with a serious and responsible attitude, helping me to develop research ideas, giving careful guidance and enthusiastic encouragement. Thanks to xu teacher's selfless help and enthusiastic encouragement, my graduation thesis was successfully completed. I want to thank you, thank you very much. He is writing a master's thesis. He took time out of his busy schedule to help me collect information, help me sort out my writing ideas, and put forward many valuable opinions and suggestions for my thesis. Express heartfelt thanks to the seniors for their help. I want to thank, thank you very much, xx students. They provided me with an important tool for writing papers-computer. Even in order to facilitate me to get in and out of their dormitory, I was specially equipped with a key, and the passwords of the four computers were told to me one by one, which made me very moved. Thank you very much for your support and help.

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