Doubtful of that, he was still looking when the storm struck.

And moreover, in taking such a step we should appear to be doubtful of ourselves.

He stared at me for several minutes, as if doubtful of my presence or identity.

As if he were the one who had a right to be doubtful of Joe's motives.

In 1923 he was highly doubtful of both sound and color.

As such, I'm doubtful of any relationship between the two.

I felt suddenly doubtful of the truth of my own story.

She studied him for a moment, as if doubtful of his sincerity.

People were "very doubtful about the motives" of some schools.

Is it because deep down you're doubtful of your own ability?