Engineering mathematics (complex variable function), engineering mathematics (probability theory and mathematical statistics), English (II), physics (engineering), simulation, digital and power electronics technology. It depends on the personal basis. If you learn math well, then complex variables and probabilities are easy to learn. Relatively speaking, physics takes more time, but it is no problem to study hard; Analog electronics, digital and power electronics are all professional basic courses. It was difficult to get in touch with them at first, so I didn't know much about them. As long as you stick to it for a while, you will be eager to get started, and these courses are very important, no matter how difficult. As for English, it really depends on personal level.