General:
* The doctor realized the futility of trying to revive the patient.
* After hours of searching, they finally admitted the futility of their efforts.
* The politician's speech was a display of futility, as he offered no real solutions.
* The old man felt a sense of futility as he watched the world change around him.
More specific:
* The futility of war was a constant theme in the author's novel.
* The artist's struggle to capture the essence of beauty was an exercise in futility.
* The rebels knew the futility of their rebellion against the powerful empire.
* The negotiator understood the futility of trying to reason with the terrorists.
Figurative:
* The waves crashed against the cliffs with a futility that mirrored his own despair.
* His attempts to win her back were an exercise in futility, as she was already deeply in love with another.
The key to using "futility" effectively is to understand that it implies a sense of hopelessness or pointlessness. It describes an action or effort that is ultimately unsuccessful or doomed to fail.