41.   But does this flaw cast serious doubts on the conclusions?

42.   But Harkin said he began hearing serious doubts about that number on Friday.

43.   But instead he was embarrassed by Wilson, leaving serious doubts about his future as a contender.

44.   But in light of the questions over the impact of IRAs in the past, there is serious doubt about the efficiency of liberalizing eligibility.

45.   But it does cast serious doubt on whether those pacts will be renewed.

46.   But now, after a series of bungles, federal financing is in serious doubt.

47.   But people on all sides of the talks predicted Monday that the money is not in serious doubt.

48.   But she leaves serious doubts about whether models will ever save the world.

49.   But privately, according to the State Police documents, they expressed serious doubts.

50.   But last month, six Massachusetts Institute of Technology scholars issued a report casting serious doubt on electric cars.