Of course, it is useful, because self-study is very hard and there is not much chance to pass, so I'd better find a good training center and take the exam after training. I have participated in the training of customs declarers in Guangzhou New Speed Education before, which is quite good. I passed an exam. Although this does not rule out that I am more talented, hehe. . . But in fact, it has a lot to do with the serious and responsible attitude of teachers in the new speed education. It's easier to understand in class and remember in your mind.