Hi, Dragontiger Used to = done or experienced in the past, but no longer done or experienced. We can use it for repeated and any other action or situation that continued for a period of time in the past. So the question is perfectly fine. There's another modal verb with similar meaning – would, but this one can be used for repeated actions exclusively. He used to brush his teeth three times a day // He would brush his teeth three times a day. He used to live with his parents. // –––

Hi, Your understanding of 'used to' appears to be okay. But in the question, 'use' is in the present not past. This is fine."Where did you use to live before you came here?" This is also fine."Where did you live before you came here?" Cheers

Great question! This is a construction that confuses learners and native speakers alike. Essentially "use to" replaces "used to" in the presence of the term "did". For example: Did you use to practice the guitar? Yes, I used to practice the guitar. Hope this helps!

Thank you so much. I understand that finally.