La expresión: "They are a couple"="Son UNA pareja" es diferente a la expresión: They are couple"="Son pareja"... Ven la diferencia?... Si "a"="Una" no es colocado en la respuesta, entonces ésta será errada pues no se apega a la expresión original mostrada por Duolingo y ha sido modificada... !!!
In some way they are alike, but the matter is how they use them, I'm going with my " couple " to the cinema and I'm wearing a new " pair " of shoes, it was a gift from my business " partner " It is only an example. Greetings
We are a couple They are a couple She and him are a couple He and her are a couple