In the broad pathways of the ocean such a chance is doubtful.
And, if we do, it is doubtful if we can attract their attention.
My errors, however, have at least made me cautious and doubtful of my own conclusions.
It is doubtful if it was mentally prepared to entertain it, or evolve the idea.
It is doubtful if many of the others were any better off in this respect.
It is doubtful if she would have realized its significance, had she seen it.
And it is doubtful if the Street would have been greatly concerned even had it known.
It is doubtful if his mind quite grasped the situation, even.
It is doubtful if any of the higher rated motors have greater efficiency.
The first one paused, doubtful which of the two dangers to choose.