Among the elements inherent to the themes related to Grammar, there is the use of the comma which, undoubtedly, is of representative importance.
Given this assumption, it is essential that we know its peculiarities, with a view to putting into practice all our knowledge in terms of the written modality. And so to speak, the article in question is intended to address the use of this punctuation mark, in view of the period composed by coordination. Let us set out, therefore, towards the realization of this intention:
# The asyndetic coordinate clauses are separated from each other by means of a comma.
Example:
The boy arrived, put his belongings away, leaned over the table without saying anything.
# Syndetic coordinate clauses are separated by commas, except additive clauses.
Examples:
I couldn't attend the birthday, however I sent my gift.
Carlos now appeared calm, now agitated.
I didn't get a good result, for I made no effort to do so.
Noteworthy remarks:
* There are only two cases in which the additives are constituted by the comma, let's see them:
# When they have different subjects.
Example:
The students were not interested, and the teacher was not keen to encourage them.
# When the connective “e” is repeated several times, thus configuring a figure of speech now called a polysyndeton.
Example:
The boys studied, demonstrated their knowledge, and won the Mathematics Olympics.
By Vânia Duarte
Graduated in Letters
Source: Brazil School - https://brasilescola.uol.com.br/gramatica/as-oracoes-coordenadas-uso-virgula.htm