71.   The medical examiner has yet to rule on the exact cause of death.

72.   The National Transportation Safety Board is investigating the exact cause of the three collisions.

73.   The researchers stopped short of identifying the exact cause of the brain damage, saying that more medical research was needed.

74.   The West Palm Beach police, however, have never formally reported the exact cause of his death.

75.   Try the victims, at least in a Pentagon report that never pinpointed the exact cause of the blast.

76.   Utility officials said it could take two days to determine the exact cause of the outage.

77.   While the Medical Examiner has not yet determined the exact cause of death, detectives say they are treating the case as an accidental overdose.

78.   While the drought and high temperatures are suspected of allowing this bug to flourish, Elliott said the exact cause may never be known.

79.   While the exact cause of the heart attack has yet to be determined, Dr. Barth Green said a massive blood clot was likely responsible.

80.   Without those clues, he said, investigators might never be able to determine the exact cause of the rupture.