I read an article about learning English for Japanese people. It says, to be good at understanding English (or maybe any second language), people need at least 3000-4000 hours of study, and they also need to learn about 3000 words. I think I had 4 English classes (4 hours in total in a week) in my high school, so if people are too lazy and study English only at schools, it will take 750-1000 weeks! wow!