1.   Although investigators are interested in the latest theory, they emphasized that they are far from declaring a definitive cause.

2.   A definitive cause for the epidemic has eluded scientists, although diet, childhood infections and exposure to allergens have all been cited.

3.   But in the absence of a definitive cause, a range of questions are cropping up.

4.   But Washington said Sunday that fire marshals had not announced a definitive cause of the blaze and that the scope of the damage was complicating the investigation.

5.   However, the hunt for potential suspects appears to be moving at an even more halting pace then the quest for a definitive cause.

6.   In each case, a definitive cause has never been found.

7.   Investigations by Belgian national authorities, the US Federal Aviation Agency, and the Montreal-based International Civil Aviation Agency would yield no definitive cause for the crash.

8.   Surging estrogen has been identified as a definitive cause of breast cancer.

9.   There is no definitive cause of the disorder other than sufferers who complain of poisoning from the surrounding environment.

10.   What little research has been done has failed to find any definitive causes.