Translation:Who taught English at your school?
I wrote "Who taught English language at your school?" and was told that it needed 'the' to make 'the English language'. As an English speaker, I'd say that was wrong. 'English language' here is a subject of study and therefore doesn't need an article. Similarly you would say 'teach history', 'teach geography' etc. No article.
In many parts of the US, it is common to just say "English" for English lit, and if someone is, for instance, in an ESL (English as a Second Language) course, they can be said to be taking an English language class or course. I agree that the answer without the article is acceptable.