Without everything being exactly right, the invocation would prove useless.

Trying to use her to take his mind off Isabel was proving useless.

I was equally certain that such efforts would prove useless.

Other small windows in each of the bedrooms proved useless.

Her efforts at pushing open either end door from the inside proved useless.

His efforts might prove useless, but he had to try.

The current financial system has proven useless at funding this.

"They're just trying to protect their test, which already has been proven useless in court."

Another door proved useless, but the third provided exactly the space he needed.

It was beginning to look as if all their defenses would prove useless.