Actually, what Kraco explaines is all pretty correct except for "shi", and mostly because "shi" isn't very used... it's somewhat archaic.
Shi - 師
Literally means "Master", not as a social rank but as someone who has mastered a certain skill. It could be translated (liberally) as a PhD, but "shi" doesn't imply the college years that a PhD does.
It's sometimes used (as far as I know) for high-ranking martial artists and people who dedicate to traditional arts such as the Tea Ceremony, but even those might be perfectly happy being called "Sensei" or "Oo-sensei" - literally "The Great Teacher"; the highest ranked amongst the profesors.
Regarding English.... I don't know. I know they take English lessons most of their life, but they still suck at it. Only College students are decent, and even then it depends on what they're studying.
In defense of them, I took English during all of grade school and highschool, and didn't learn a thing. Nobody learns anything at highschool
(How did I learn English then, you ask? Reading. With a dictionary.)