I can say in Spanish,
Yo jugaba al tenis cuando tenía 8 años,
which means
I used to play tennis when I was 8 years old.
I could also ask,
¿Jugabas tú al tenis cuando tenías 8 años?
whose English counterpart is
Did you play tennis when you were 8 years old?
Sometimes I get stuck, though, since it's hard to ask
Did you use to play tennis ...
Is there a real way to ask a question in the imperfect using the "used to" form of the imperfect?