Let’s see the way we use “used to” (simple past):

used to = obisnuiam sa

This form is only for affirmative sentences. “Used to” is followed by the bare infinitive of the verb

I used to sing a lot when I was a kid.

I used to wake up early when I was young.

For negative sentences we need the auxiliary verb of simple past: did (“did not use to”)

We didn’t use to have a computer in our childhood.

I didn’t use to live in a big house.

We also need the auxiliary verb did to form the interrogative sentences:

Did you use to spend your summers with your grandparents?

Did he use to ride his bike to school?

Did she use to work with you?

When do we use:

We use “used to” when we need to talk about:

1. those habits or things that happened in the past

He used to drink a lot of coffee.

My best friend used to smoke.

I used to play football a lot.

I used to study early in the morning.

2. Those situations that existed in the past but no longer exist

Mary used to be the best student in class, but now John is the best.

I used to live in Spain.

My mother used to work in advertising.

3. it’s important to express the contrast between the past and the present

We used to go to school by bus, now we use cars.

I used to go to bed late, now I get tired at 10 p.m.

My son used to eat meat, now he is vegetarian.