"We gave back the sandwiches."
Translation:Nous avons rendu les sandwichs.
Apparently it is linguistically correct, but not the most common way the French would say it.
I suspect it is another example of their desire to "introduce" something before then referring to it by/with a pronoun.
So, they first say the thing: "Les sandwichs, " Then they say a sentence where it is referenced: "nous les avons rendus".
Notice that said the direct say where "Nous avons rendu" comes first, that the "rendu" has no 's' at the end.
But, in the more French way, the thing(s) has (have) been mentioned, so the "rendu" requires an 's' to agree in gender and number.
"Les sandwichs, nous les avons rendus."
This figure of speech is called "emphasis by extraction", where either the subject or the object are said upfront, "extracted" from their natural place, then repeated with a matching pronoun.
In "l'Etat, c'est moi", you can see that "l'Etat" is the emphasized word. Without this emphasis, Louis XIV could have said "Je suis l'Etat" (I am the state), where "l'Etat" is a descriptor of the subject "je". The pronoun used to refer to "l'Etat" is "c'."
He could also have extracted the subject "je", which then would have become as a stressed pronoun starting the sentence: "Moi, je suis l'Etat".
In "les sandwichs, nous les avons rendus", the emphasis is on the object "sandwichs" and the pronoun is "les". Without the emphasis, the sentence would read: "nous avons rendu les sandwichs".
Yes, but the ultimate issue here is that, when translating from English, "Nous avons rendu les sandwichs" is being dinged as incorrect, with the emphatic form of the sentence being given as the only acceptable response. Clearly, Duolingo is incorrect in only allowing one arrangement for the sentence (and I have reported it).
That said, thank you for this clarification.
The quote refers to subject nouns - e.g., "L'état, c'est moi." In this example, though, "les sandwichs" is the object noun. There's no particular reason that the object should come at the beginning of the sentence, otherwise the past participle ("rendu") would always have to agree with the object. This course is full of examples where the object comes after the verb, though, and basic word order in French tends to be subject-verb-object.
No. If the French tend to use the emphatic construction with "subject noun - comma - repetition of the subject as a pronoun - verb ..." it means that the compound verb now refers back to the DO so requires agreement.
FR "Les sandwichs. nous les avons rendus
EN "The sandwiches, we gave them back"