I'll jump on the English side of this and confirm that "you could drink wine" is one way to express "you can drink wine" in the past tense. As such it can be synonymous with "you were able to drink wine" and should be accepted here, which follows logically regardless of the exact sense of the French.
For those suggesting "you could have drunk wine", that's perhaps a bit of a stretch. Technically it corresponds better to "vous auriez pu boire du vin", but I suppose it could depend on the context or the interpretation.
Edit: One distinction that can be observed with respect to the two past-tense constructions is that past-tense "could" denotes only possibility, whereas "was/were able to" can also be used to denote actual achievement, depending on the context: "we were able to get the letters sent" (which we proved by actually sending them) versus "in those days we could drink wine" (and perhaps we did).
In the negative, the two past-tense constructions are generally equivalent: "we weren't able to get the letters sent" is the same as "we couldn't get the letters sent".
DL appears to be inconsistent re: allowing/disallowing "you could" as a translation for Past Imperfect.
For example, in the Past Imperfect skill (crown level 2), «Je ne pouvais pas dormir» is translated to "I could not sleep".
In the below Gavier (a MOD) confirms PeaceJoyPancakes comment: "Due to the oddities of English "I couldn't sleep" can be either past (I couldn't sleep last night) OR conditional (I couldn't sleep in a place like this). The French "je ne pouvais pas dormir" is past tense."
Pouviez is in the imparfait, but pouvoir is almost always used in the imparfait rather than the passé composé (and in fact it has a different meaning in the passé composé). "Could [have]" is simply the past of "can," and I would say more idiomatic than "were able to," and thus should have accepted.
In French "pouvoir" has a double meaning : capacity and authorization. So you are right, we have to use "be able" for capacity. But you can perfectly translate "You could drink" if it is an authorization. As usual DL refuse a meaning although the sentence do not contain any form of context. It is painful and anti pedagogical. They have to correct that.
Hmm, I can't find a way to explain it in proper grammatical terms, but when I sound out the sentences to myself (as a native English speaker), "You could have drunk some wine" seems like a perfectly acceptable replacement for "You were able to drink some wine," which is how DL has translated the phrase. If you add a time period, "You were able to drink wine on that night. You could have drunk wine on that night" it's clearer. Maybe English evolved this construct to differentiate between "could" being used as conditional ("You could drink wine that night" - it doesn't sound past tense) and being used as past tense.
It seems to me that the English equivalent here would best be "You could have drunk (or drank) some wine" I know there is no avoir used but to me it sound more natural in English and using "could have " indicates an action in the past , one of the correct answers is "you could drink wine" which is really a present tense to me at least indicating an action that could take place.
I think "you were able to drink some wine" should be a correct translation. "You used to be able to drink some wine" is listed as correct. While it's true that 'used to' and 'were' don't always carry the same connotations, it's still possible that 'were' could be used in the same sense that 'used to' is.
I'm pretty sure DL will recognise that as conditional tense, as in 'you would be able to'....could can be used in English to convey a previous ability, but it doesn't really convey the true meaning of French imparfait tense, which is really about establishing back story for a narrative, explaining something which was taking place as a rule around the person or event being discussed, so the true essence of it would be more like "In those days, you used to be able to drink". Does that make sense? HTH! :)
I'm also fine with Duo trying to draw a distinction between imparfait and conditional, but I think that any way that incorrectly polices English usage is an absolutely terrible way to do that, as is any way that will improperly constrict what learners think are appropriate ways to use the tenses. Unfortunately, the best way to do so, using far greater context, is pretty much unavailable on the duolingo platform, but there are nonetheless better ways.
And ... why am I not just reporting and shutting up? People use the lessons to learn the language, but they go to the comments to understand it, which principle it seems you're pretty familiar with.
I wasn't saying that you told me to shut up; I was merely responding to your implications, with regard to my first comment, that doing so would have been a far better course of action:
"Don't tell me, tell Duo."
"... so report it and get it fixed if it bothers you. "
"... pointing something out to me, which [in these circumstances under which I should be confining my comments away from this thread] is impotent and futile."
... which is why I said "why am I not reporting and shutting up?" instead of "You can't tell me to shut up" or something like that.
"could can be used in English to convey a previous ability, but it doesn't really convey the true meaning of French imparfait tense" [emphasis mine]
My point was that the idea that imparfait has a true meaning, which is poorly represented by "could", seems ... a little misplaced, when "could" is probably the most common way in English to convey previous ability. It's almost like (to use an admittedly rather excessively hyperbolic comparison) insisting on using "être en train de" to translate the present continuous from English because the present indicative doesn't convey the true meaning.
Good point well made. Can see a little better where you're coming from, and you're quite correct. It's an important distinction, and it bears further discussion, I imagine you already have reported it. My original comment was not supposed to be dismissive, I genuinely want Duo to be as good as it can be, so I always encourage people to report. Came across dismissive though, my bad.
Don't tell me, tell Duo. I'm totally fine with Duo trying to draw a distinction between imparfait and conditional, but clearly you're not, and I have seen 'could' accepted for other questions, so report it and get it fixed if it bothers you. Also my post already acknowledged the use of could in English beyond conditional tense. :)
I think "You could have been drinking some wine" should also be accepted. It's a continual action that is in the past.
I used to think that "You could've drunk some wine" should also be accepted, but now I'm not so sure. That implies a completed action, but not a repeated completed action.
This translation is really tricky and I wish that some experts would weigh in more fully. Please!
Although many actions in the imperfect are interpreted as "used to" or "was" sometimes they look like the past perfect. Since pouvoir means can or to be able to, It makes sense to me that "you could have drunk some wine" would be the strongest interpretation. You don't need to insert avoir to have a proper interpretation of this imperfect form. Some things in the past require a helping verb but here it is implied in the imperfect structure. I agree with you. Then how would one say "you could have drunk some wine"?
In languagecenter.cla.umn.edu, instead of "used to", they translate imparfait repetitive actions with "often". In other words, an interpretation such as "you were often able to drink wine" would be used. This eliminates the sense of "used to" which indicates that the action is no longer happening, and that there has been some resolution of the action. To some extent, ability to drink wine is like a process ... so being able to do it or not ... what an English translation of imparfait should convey is no sense of whether the action is still true or has stopped, and what passe compose should convey is a sense that the action has concluded. In that sense, the translation "you were able to drink wine" also seems reasonable. In the language.cla.umn.edu website, the discussion around imparfait translation suggests that the action feels incomplete, like something needs to follow to say what happened next.
"Ils ne pouvaient pas dormir." A correct response according to Duolingo: "They couldn't sleep."
"Je ne pouvais pas dormir." A correct response according to Duolingo: "I could not sleep".
"Vous pouviez boire du vin". A correct response should likewise be 'You could drink wine', but this is marked as incorrect.
I am surprised that "allowed" was accepted, if it was, they should also accept permitted because they are synonyms. However, this sentence to me is not suggesting permission but rather ability - you could drink wine, not you were allowed to drink wine. The first suggests choice whereas the latter suggests needing approval.
If anything, it would have to be "pourriez", i.e. conditional rather than imparfait: "Vous pourriez boire du vin si vous vouliez." And I think that sounds more like a suggestion than an offer, though I suppose it could imply an offer in the right context.
For an offer, I imagine you could just say "Vous prenez du vin ?"