The voice is good and the lecture content is not bad overall, but I don't understand why the lectures are cut off at such a short time and move on to a new lecture. I wish the lectures could have lasted at least 10~15 minutes, but there are many lectures that are too short, like 2~4 minutes, so I think it breaks my concentration. It's like when I take a class at school and the teacher says, "Let's teach for 5 minutes and then take a 1-minute break."