"We came back very late."
Translation:Nous sommes rentrés très tard.
Why is the second alternative, 'Nous rentrions..." accepted? I thought using the imparfait implied the action was ongoing, recurrent or incomplete?
You are right, "nous rentrions" should not be accepted:
nous rentrions très tard à cette époque (habit) = we used to come back...
nous rentrions très tard quand la voiture est tombée en panne (lasting action) = we were coming back...
In the three sentences presented (to me), the other two were completely off, the "nous rentrions" was the closest. On the other hand, I understand that the imperfect past can be used in the sense of "setting the scene", in which case its use could be accepted here if we overlooked Duo's habit of dropping the second action that was either going on at the same time or interrupted the first one.
Not just "ongoing" but it refers to the fact that the action was in progress at some point in the past; in this context, it is normally juxtaposed with a second phrase which refers to another action that was also taking place or that happened (passé composé) while the first action was taking place. The second phrase is absent in Duo's example and leads us to question if it is a valid application of the Imperfect tense. Given that the imperfect can be used to "set the scene", it could be used, except that the next action is missing (a common fault in Duolingo). The opening line in a mystery story: "We came back very late that night when suddenly, it happened". http://french.about.com/od/grammar/a/pasttenses_2.htm So the question is, are we willing to overlook Duo's abbreviated version in an effort to learn from it?
In French, comparing "revenir" and "rentrer", the latter means "come back to where you belong (home, hotel...)", whereas the former does not convey/specify that notion.
I still don't understand why revenir or retourner can't be used here. We only know that the "speaker" is part of the subject, and came back very late. But we don't know where they came to, or where they are now. That context is critical, according to: https://www.frenchasyoulikeit.com/retourner-revenir-rentrer-whats-the-difference/
"Revenir" can be used: "nous sommes revenu(e)s très tard", but "retourner" needs a destination to mean "come back": "nous sommes retourné(e)s là-bas/chez nous très tard".
With the meaning of "came back" or "returned home", the French use "rentrer" which can stand alone to mean exactly that.
You know, I kind of like "explicit" as a verb in that sentence. It's concise. However, I'm afraid that in English it is only a mere adjective. You would have to say "does not make that notion explicit," or perhaps "does not specify that notion".
Don"t you guess?
rentrés is masculine: "we" is all men or a mix of men and women
rentrées is feminine: "we" is all women
Passé composé = compound past.
Compound = in two words
"Sommes + rentré(e)s" = 2 verb forms: 1 auxiliary + 1 past participle
"Sommes" is the auxiliary "être".
With the auxiliary "être", the past participle agrees with the subject.
"Nous" can be masculine of feminine.
"Rentrés or rentrées" are possible, correct and accepted.
why cant i do "nous avons rentres tres tard"? since they used the 'have' word for past verbs before.
"rentrer" is an "être" verb.
You will use it with "avoir" if there's a direct object: nous avons rentré les chaises (we brought the chairs back in).