1.   The precise cause of the break May in fact never be known.

2.   The precise cause of this serious disease is still unknown.

3.   The precise cause was open to debate.

4.   The precise cause of the disease is unknown.

5.   The precise cause of the collapse of the talks was unclear.

6.   And officials did not disclose the precise cause of death.

7.   A precise cause of death has not been determined, according to Peter Connell, the director of the Connell Funeral Home, which is handling the arrangements.

8.   But the precise cause continued to elude researchers.

9.   But they acknowledge that determining the precise cause of the detonation may be beyond their grasp.