51.   It was already known that a major threat to the cichlids of Lake Victoria was the Nile perch, an introduced species known to be a voracious predator.

52.   It is unclear if Linux will become a major threat to Microsoft or just an interesting dead end.

53.   Like Galvin, Marks believes only a major competitive threat will be able to keep Fleet in check.

54.   Major flooding threats continued along the Russian River, in the Sacramento and Monterey-Carmel areas in Northern California and in various parts of Southern California.

55.   Middle East quarrels, driven more by religious extremism than by the more secular groups in the past, still represent a major threat to the United States.

56.   Meat is dangerous particularly because of the diseases it can bring, such as foot-and-mouth disease, a major threat to cattle.

57.   Most important, will West Nile pose a major threat to public health in the United States?

58.   Now that garage sales have allowed the Chicago Bulls and Orlando Magic to become major threats in the free-agent mall, expect the tactic to be repeated.

59.   Observers said none of the summary judgment motions, even if granted, are likely to pose a major threat to either side.

60.   Now comes another painful blow, all the more so considering how many major threats have been eliminated.