This is just a guess but I think I read that DL use algorithms to construct phrases so that the lessons and practice sessions are not always the same - nouns, verbs, tenses etc.. are switched around by the DL algorithm rather than human prepared examples. While this may end up with phrases like the red elephants live in Spain and like cheese (I made that one up), it is still linguistically correct and allows for more variety in each exercise rather than just dragging out the same exercise over and over again. However, I may be wrong.
Actually, nosotros can mean either "us" (male) or "us" (male+female mixed group). And as TilEulenspiegel mentions, "Nosotros" in this case is the subject of the sentence. Nuestra is modifying madre, & since madre is feminine, we need the "nuestra" form of the possesive pronoun, "our." Paz.
Guess this is an English question, but how or why would one use We had know or mother rather that We knew our mother? or course same time... google translate recommends a translation of "we had met our mother" which makes seems to make better sense, mutiple uses, more useful etc. lol
@SamuelBoas: First the terminology: - "knew" is called the Simple Past (only one word); - "had known" is called the Past Perfect". If you just want to say that something happened in the past, you use the Simple Past e.g. "we ATE at 6 o'clock". But if you want to stress that something happened BEFORE something else in the PAST, then you've got 2 points of time in the past. In that case you use the Past Perfect for the earlier action and the Simple Past for the later action e.g. "We HAD EATEN before John ARRIVED". - "had eaten" (Past Perfect = first action) - "arrived" (Simple Past = later action) I hope that helps. By the way, what is your first language?