枉费

The reactionary government tried vainly to take the steam out of the protest movement.

反动政府枉费心机地企这场抗议运动。

They tried in vain to persuade her to go.

他们极劝她去，但枉费了一番口舌。

Those who protested against the president's decision were actually barking at the moon, since they were in a powerless minority.

于他们属于软无的少数, 他们反对总统的决定实际上枉费唇舌。