I just do computer maintenance. I taught myself at first, but I personally think it's more direct to find a technical class to learn, because what you learn from books is not necessarily useful in practical operation, and the progress must be very slow. In the technical class, one person has one machine, and I learn faster. Later, I studied in a Beiyang computer maintenance class in the north gate of Nankai Tianjin University, and I felt that what I taught was more practical.