The lower board proved more stubborn, two of the nails bent.

The man I thought might know has proven stubborn.

One had proven much more stubborn than the other.

Why did this particular man, who had already given him so much trouble, have to prove so stubborn?

Where the wood proved stubborn and resisting, he let it be.

But Japan's slump has proved stubborn, and costs have bloated.

The wife proved more stubborn, and the magician did as asked.

Among the fires burning in Colorado, two others were still proving stubborn.

The reason this state of affairs has proved so stubborn is simple: scarcity.

At that time, in 1971, much like today, unemployment was proving particularly stubborn.