I have an inexplicable affection for radish net ... I have heard it several times and it is very good. I'm sure I didn't read by the book. There are some teachers who I think are excellent. And you can control your speed by listening to the courseware. As long as you concentrate, the learning effect is quite good ~
It's really not at ease to open the course page and listen to the class. They are all extracted from formal courses, mainly depending on whether you like this teacher or not. You can still make a preliminary judgment through audition.