All right. According to relevant public information, Yan Na, a first-class registered construction engineer, has more than ten years of professional training experience and on-site management experience of large enterprises. Over the years, I have been teaching the course "Management and Practice of Mechanical and Electrical Engineering" for first-and second-class builders for a long time. He has edited 20 Yu Ben teaching AIDS and several training handouts, is familiar with the rules of the first-and second-level constructor exam, is good at summing up, and can apply learning methods and exam-taking skills to teaching to help candidates pass the exam quickly.