Teachers are generally unreliable, because no organization can guarantee that the strongest teachers will give you lessons, so you need to find a balance between the second and third points. For the form of classes, small classes are undoubtedly more effective than large classes, and the arrangement of courses is closely related to the research and development of institutions. Some organizations say that the interview is very complicated, which is a means of the market. In fact, the interview is actually very simple, that is, theory, practice, heat, and so on.