Em Brasileiro, a locução 'Eu fui..' e 'Eu ia\costumava ir' expressam contextos diferentes.
Eu fui à Monte Verde.. ( provavelmente uma vez, ou poucas.. )
ao passo que 'Eu ia\costumava ir ' à Monte Verde sinaliza que eu ia lá habitualmente, com uma certa freqüência.
Pois bem, eu fui = I went, enquanto que eu ia\costumava ir = I used to go..
1- I used to live on the beach, now I live in the capital. vivia\morava ou: vivi\morei = I lived (naquela ocasião, época)
2- I used to come to work by car, now I come on foot.
vinha\ costumava vir ou: eu vim = I came (uma vez..ontem)
3- I used to play tennis..(I don't play anymore anymore)
jogava\costumava jogar ou: eu joguei =
I played football yesterday\last weekend
4- My sister used to believe in Santa Klaus when she was a kid
(she doesn´t anymore) acreditava ou: acreditei =
I believed that story you told me yesterday but it wasn't true, was it?
5- Daniel and Jesse used to have more free time before they had kids. tinham\costumavam ter ou: tiveram =
They had a 2-week holiday with the kids back in January
6- Claudio used to go to the movies more often.. (he still might go, yet not so often) ia\costumava ir ou: foi =
He went to the movies on Saturday with his girlfriend.