Peter knew that if Daniel had proved more tractable, he himself would already be dead.

"Let's pray that this new candidate proves more tractable, or we will be in deep trouble indeed."

But he had proved amazingly tractable.

The unspoken threat was that unless they proved tractable, he would get them.

I can promise you the same eternal youth, my dear, if you prove tractable.

I hope these prove more tractable than the others.

If the prey had proved tractable, our present foray might have become a base of operations.

Larsen said: "You'd better hope Lord Worth proves more tractable than his daughters."

If they would only prove tractable once she had the gear!

Withdrawal, the physical and mental turmoil that follows when an addiction is interrupted, is proving more tractable to experimental analysis.