"My mother and my father went to eat soup."
Translation:Minha mãe e meu pai foram tomar sopa.
Duolingo rejected my translation "Minha mãe e meu pai foram para tomar sopa". Which I suppose is really something like "My mother and father went in order to eat soup". Acceptable or not? O que você acha?
A good explanation to use "para" in this context should be "Minha mãe e meu pai foram (ao restaurante para) tomar sopa". "Para" means a purpose for sonething you do or going, in this case they just went for the soup no matter where they're going.
What is the rule for when to use "a" before a verb. For example, I wrote: Minha mãe e meu pai foram A comer sopa. When should one use the "a" and when not, please...
It depends on whether the previous verb demands a preposition (which may not be "a", it could be "de" or "por", etc). Here the previous verb is "ir" and you will recall from phrases like "Eu vou cantar" (I will sing) that it does not require a preposition when followed by a verb in the infinitive.
A good example of a verb that demands "a" is "começar" (to start) and you would have to write "Meus pais começaram a tomar sopa".
Mesmo que não precisa uma preposição, às vezes se possa usar uma para dar mais ênfase como cinthiia_mc confirmou.
In English we would generally just say my mother AND father. Although not wrong in English to say my mother and my father it is less common and in my opinion adds a degree of formality and perhaps emphasis to the statement.