Para algo que era cierto antes pero ya no lo es, di used to + el verbo tal cual.
used to + verbo tal cual
I used to play tennis. (but I stopped)
Amina used to live near the harbor. (now she lives downtown)
We used to walk to school every day.
Not "I use to play tennis." — say "I used to play tennis.". Aquí lleva la -d: used to. Significa que lo hacías antes, pero ya no.
Pruébalo: Amina ___ live near the harbor, but now she lives downtown. (used to / use to / uses to) Respuesta: used to — Para algo que era cierto antes y cambió, usa used to, con la -d. "Use to" (sin -d) y "uses to" no son la forma de pasado aquí: she used to live there.
didn't use to
Para decir que algo no era cierto antes, di didn't use to + el verbo tal cual. Después de didn't, quita la -d: es use to, no "used to".
I didn't use to like coffee. (now I do)
She didn't use to study hard.
We didn't use to have a car.
Not "I didn't used to like coffee." — say "I didn't use to like coffee.". Después de didn't, no hay -d: didn't use to.
Pruébalo: I ___ like coffee, but now I drink it every day. (didn't use to / didn't used to / don't use to) Respuesta: didn't use to — Las palabras están bien, pero después de didn't no hay -d: didn't use to (no "didn't used to"). Y para el pasado necesitas didn't, no "don't".
Did you use to ...?
Para preguntar, empieza con Did + la persona + use to + el verbo tal cual. Otra vez, después de Did, es use to sin -d.
Did you use to play tennis?
Did she use to live here?
Where did you use to work?
Pruébalo: ___ you use to play tennis? (Did / Do / Were) Respuesta: Did — Para preguntar sobre el pasado, empieza con Did: Did you use to play tennis? "Do" es para el ahora, y "Were" es para lo que alguien era, no lo que hacía.
Pruébalo: She ___ smoke, but she ___ exercise much — she never went to the gym back then. (used to … didn't use to / use to … didn't used to / used to … didn't used to) Respuesta: used to … didn't use to — Por sí solo mantiene la -d: used to smoke. Pero junto a didn't, la -d desaparece: didn't use to. La -d está en la frase simple y desaparece después de did/didn't.