If you are talking about closing something physical, like a door or a store:
* abran: This is the imperative form of "abrir" (to open).
* ábranse: This is the more formal version of "abran".
If you are talking about closing something abstract, like a meeting or a project:
* abran: This still works, but you might need to specify what is being opened, like "abran el debate" (open the debate).
* continúen: This means "continue" and could be used to indicate that something is not closed but ongoing.
* retomen: This means "resume" and could be used if something was closed and is now being reopened.
Example:
* Cierren la puerta. (Close the door.)
* Abran la puerta. (Open the door.)
* Cierren la sesión. (Close the session.)
* Continúen la sesión. (Continue the session.)
It's important to consider the context to choose the most appropriate opposite of "cierren."