"My parents are adults."
Translation:Mis padres son personas adultas.
mis padres son LOS adultos. I hesitated for a few moments and added LOS here and was marked wrong. I still have no clue about when to use article and when not in Spanish. No gut feeling either. I put this sentence in Spanishdict, to give it a test. With los, one dictionary trasnlated as My parents are adults. two of them translated, My parents are the adults. without los, all translated as my parents are adults. none said it is not acceptable sentence.