can they always be used interchangeably?
esta noite seria diferente se não estivesse chovendo. = esta noite ia ser diferente se não estivesse chovendo.
thanks in advance!
I'm not sure why, but to me "seria" represents the conditional (This night would be different, if...), while "ia ser" means "was going to be" (close/immediate future). Is there any distinction in BP that explains that conflation in your mind?
Luis, this sentence could be used to express the idea that you expected something to happen, but it didn't.
Esta noite ia ser diferente, mas no final, tudo ficou o mesmo como sempre!
I am not sure that using "seria" works the same way.
it's a bit confusing for me, because in english, "this night would be different," does convey an expectation, but doesn't imply whether or not the outcome matched the expectation. i get that would have been in portuguese requires the participle sido, and not the infinitive, but.. the sense of the two sentences confuses me, in short.
That's correct - I'm not sure "seria" could convey the same idea either.
if that's the case, then could i use "tonight would have been different"?
"Used to" always asks for the imperfect - either "era" (from ser) ou "costumava ser" (sounds slighly weird since "costumar" means "having the habit of", but it still works if you see something different in "this night" that's not normal/habitual).
Luis, Whitlam uses "costumar" in the imperfect as you have suggested but notes that it sounds rather formal /literary and is not often used in colloquial speech. He is talking about Brazil. He translates it as "used to". Is it used in Portugal?
Yes, it is aldo used in Portugal (I can't vouch with certainty if it's more formal and/or common there than here, but it's rather common for regular activities when a habit is formed).
I'm not sure if Whitlam was talking just about the imperfect in that occasion, but "costumar" can also be used in the present for regular activities people keep doing (Eu costumo jogar tênis/ténis no fim de semana. I usually play tennis on the weekend).
What it can't translate is "to be used to" (I was used to having him by my side; I'm not used to hurricanes) which are better translated with the adjectives/past participles "habituado/a" and "acostumado/a" (which follow from costumar, of course; costumar = costume = habit/custom).
Whitlam uses costumar + infinitive in the present: "to be in the habit of, usually.
Costumo correr de manhã = I usually go running in the morning.
As a BP native speaker, I think that Duo's translation is perfect. It shows exactly the idea we want to convey in Portuguese.
"Tonight it was going to be different" what stops me from translating it like that?
The word "it". The sentence is taking about the night, when you add a word referring to something else, the translation becomes wrong.
"Tonight was going to be different" and
"Tonight it was going to be different" mean different things
So then how would I say the second sentence? Since I was under the impression that when "it" is the subject, you simply conjugate the verb in the third person singular
I would translate the second sentence as
"Esta noite, isso ia ser differente.
I've just added the word "it" and I'm not 100% sure it's right, but that's how I would do it. Or maybe:
"Esta noite, que ia ser differente"