It's 'useless' trying to change her mind. = It's 'useless' to try to change her mind.
Drugs are 'useless' in treating the condition.
I made a 'useless' attempt at fixing the leak.
(..) You know what a poozer is, don't you, poozer? - No, sir. DEEGAN: I can't hear you! No, sir! Poozers are what I call useless, stupid, stinking rookies... ...like Brilowog over here. - Kilowog, sir. Did you just say something, Brilobutt? No, sir. Sorry, sir. (..)2011 Green Lantern: Emerald Knights
(..) Use your imagination. HAL: It was too much for them. For anyone. WACHET: These rings are useless. We might as well be wearing trinkets. What do we do? We have only two options: Retreat or death. There is no victory here. (..)2011 Green Lantern: Emerald Knights