to express worry or doubt about an issue
expresar preocupación o duda sobre un tema (expresar preocupacion o duda sobre un tema)
"Activists raised concern about the pollution levels in the river."
"Los activistas expresaron preocupación sobre los niveles de contaminación en el río." (Los activistas expresaron preocupacion sobre los niveles de contaminacion en el rio.)
to talk about a particular topic or issue
to claim or pretend something about someone or something
to reach an agreement after discussion or struggle
to prepare to compete or argue directly with someone
to become familiar with or accustomed to something new
to set suggestions aside for future review