On Wed, 5 Feb 2014 19:55:18 -0200, Guilherme Santos <[log in to unmask]> wrote:

>I heard that there are languages where adverbs agree with the words they
>modify, but, as they can modify basically everything, i have no idea in
>what would they agree:
>Would they have different forms when modifying verbs or adjectives?
>Do they inflect in everything the words they modify inflect?
>I googled it an found no examples of this agreement.
>I want to used that in my conlang, but i have no idea how exactly that
>would work.

I have a conlang example of this.  In the Peninsular family of Akana, and in particular in my Kibülʌiṅ, adverbs agree with the verb in the category called _phase_ in Peninsular generally, and _grounding_ in Kib., which has developed from something like aspect to a purely information-structural category.
The closest Kib. has to adjectives are stative verbs, which have the same morphology as other verbs, so there's no difference in adverb agreement there.  If they found themselves modifying other words, in a way that couldn't be understood as the reduction of any clause, they'd probably not be considered adverbs anymore and dispose of the grounding suffixes. Indeed, providing the grounding suffixes alone is a way of converting non-adverbs to adverbs in Kib.:
  _pī_ 'day', _pij-u_ 'during the day'
  _ttej_ 'one', _ttejʌ-u_ 'once'

Mind that it's not a universal truth that "adverbs can modify basically everything"; different languages divide up word classes differently.  Indeed, in standard English schoolbook grammar, the "adverb" word class is a bit of a dumping ground for words which don't seem to fit well anywhere else, which makes its behaviour look somewhat more heterogeneous than it ought...