"She writes for children and for adults."
Translation:Elle écrit pour les enfants et pour les adultes.
is it incorrect to say 'pour les enfants et les adultes' or must you repeat prepositions like 'pour'?
No it is not incorrect, repeating words only serves to insist on something relevant.
"les enfants" = children in general "des enfants" = some boys in particular
why des enfants et pour des adultes is incorrect? when do you use les instead of des
In this sentence the children and adults are a generality encompassing all children and adults, so you must use les. If it was referring to some particular group of children/adults, then you could use des.
Again, this is why I don't like generalisations. If you walk up to a group of girls, you'll address them as "LES filles". You're most certainly not greeting all of the women on the planet.
It's because the 'le/la/les' group can refer to either an exact thing that you're talking about, or a generality (or category of things, however you prefer to conceptualize it). The 'du/de la/des' series is for an unspecific/indeterminate amount of something. If je mange des pommes, we don't know how many apples I'm eating. In the most basic sense, it replaces the word 'some'.
Your example is correct as my original explanation was not very clear or complete.
And of course there are still other exceptions and usages for the partitive and other articles.
they made me fail cause i translated des instead of les.that is an unproper discretion
I swear this sentence is correct. Why was it marked wrong "Elle écrit pour les enfants ainsi que les adultes"