To be honest, this is a review based on this course. This person, first of all... isn't particularly good at explaining... and isn't particularly good at speaking either... While listening to the course, there are quite a lot of cases where you think "let's just accept this for now and move on... I'll look it up separately later..." Of course, it's natural to look up parts you don't understand, but when you see the results of looking things up, rather than not understanding the concept... it makes you feel like "what was this person trying to say?"...