Sentence examples for is difficult to prove from inspiring English sources

That is difficult to prove.

"It is difficult to prove," he said.

However, that is difficult to prove.

Perjury is difficult to prove.

Ownership of ideas is difficult to prove.

It is difficult to prove a concert action.

Arabian influence on European medieval music is difficult to prove.

But it is difficult to prove that they did so knowingly.

So it is difficult to prove the motive in the court.

Later, it is difficult to prove that the perpetrator had used false identity.

And it is difficult to prove*.