The thesis should be based on meaning, and the beginning and end mean the center, brain and commander of the article. If you want to write a good paper, you must grasp the center. The requirements of this center should be simple and clear, can be summarized in one sentence, and can achieve the purpose of simple management and complexity. Grasp this center, stick to it, go all the way to the end, don't change the topic halfway, don't stop, don't jump, so that the development of the central idea can be continuous.