Imperfect vs past tense
They never wanted my picture.
Duolingo says that "Ellos nunca quisieron mi foto" is correct, but shouldn't the verb querer be in the imperfect because the meaning of the word changes in tense?
I think it should be; "Ellos nunca querrían mi foto.
My understanding of the difference is that imperfect implies a longer time or ongoing situation while preterite usually refers to one occasion, so I would agree with you; putting in nunca extends the period of time. However in real life there is American/Latino Spanish and Castillian Spanish. Just like with English: a US speaker might say "he never wanted my picture" and it could mean - on that occasion he didn't want my picture", while to a UK English speaker it would have a different meaning "he never wanted my picture" (even though I offered it to him every day). I would argue that both versions should be allowed by Duolingo.