11.   Gingrich seems to doubt their sincerity.

12.   I do not doubt their sincerity.

13.   I have no reason to doubt his sincerity, but the means matter as much as the ends.

14.   If it were too sound, the judgmental fashion insiders might doubt the sincerity of her mourning.

15.   Issel cried at a Wednesday news conference, and few doubt the sincerity of his apology or the depth of his embarrassment.

16.   Just because a vice president hangs around with penniless Communist bureaucrats who turn into Donald Trumps overnight, people doubt your sincerity.

17.   Leaders of the cable industry also say that they doubt the sincerity of network television executives, who have promised to begin broadcasting high-definition programming next year.

18.   Minkow said not surprised that some would doubt his sincerity, for he doubted himself.

19.   Not that I doubt his sincerity.

20.   No, they felt only sadness for the country, they said, even if the Democrats doubted their sincerity.