“We shot him doubtful looks, certain that the country that gave the world the deep-fried pizza would be incapable of producing anything near the standard of a Mint Slice.”

“They are doubtful of her being reunited with Ollie, after waiting more than two weeks for his return.”

“It is doubtful whether tomorrow's victor will reach quite those lofty heights, but No Kidding is a horse with a bright future, nevertheless, and he is fancied to oblige.”

“… a doubtful claim to the property.”