Alternatively, in the languages I speak:

Welche Sprachen sprechen Sie? (Deutsch/German)

¿Qué idiomas habla usted? (Español/Spanish)

Quelle langue parlez-vous? (Français/French)

EDIT: These sentences are now up to date.

  • Yeah, it is the hardest thing when learning a new language. When you learn a new concept that your language doesn’t use. For example, in Latin, German and Japanese, the grammatical case is very important but totally irrelevant in French and English. So I try when I speak French or English to think about the case. That way it comes more naturally to me when speaking German or Japanese.

    • Yeah, the catch here is that it’s a feature that my native language does at least sort of have, just applied in a way that makes it not clear. When it’s a feature I’m completely unfamiliar with, I’m more likely to be on guard for it, if I’ve learnt it. But here I didn’t even think about it, because it was an element I am familiar with, so I never second-guessed my intuition, even though that intuition was wrong.