I believe "Tu înveți engleză?" is incorrect. The Romanian should be "Tu înveți engleza?" or "Tu înveți limba engleză? "
Actually, Wyqtor, "Either variant is correct" is a meaningless remark when three versions are referred to and one of them ("Tu înveți engleză?") is wrong. ;)
Fair enough, I am sorry and I take your point, but you didn't mention you were a native speaker. I was confused by your use of "either variant" where three were being mentioned. Could you explain whether "Tu înveți engleză?" and "Tu înveți engleza?" mean exactly the same thing and whether there is any difference in usage? Thanks in advance!