antes

In a sentence

• Antes de sair, verifique se você pegou tudo.

  Before leaving, double-check that you have everything.

  Here, 'antes' is used as a preposition meaning 'before', indicating that the action of leaving is preceded by another action.

• Você deveria ter chegado antes.

  You should have arrived earlier.

  In this sentence, 'antes' functions as an adverb meaning 'earlier', expressing an action occurring in a prior time compared to another reference point.

• Antes eu pensava diferente, mas mudei de opinião.

  Before, I thought differently, but I changed my opinion.

  Here, 'antes' is also working as an adverb, positioned at the beginning of a statement to set the time frame for the following description of a past habit.