21.   It was not clear whether the injured men knew their assailant or whether one or all three took part in the argument, whose cause was not known.

22.   Neither the funeral home nor the company knew the cause, and family members could not be reached.

23.   No one knows the cause of this problem.

24.   No one knew the cause, although the problem was eventually diagnosed as a severe form of repetitive-stress syndrome.

25.   No one knows the cause, or has a cure.

26.   Officials admit they may never know the cause of the accident.

27.   Officials from several city departments said they did not know the cause of the break, a seven-foot fissure half an inch wide.

28.   One lawyer said the issue might come up again once the cause became known.

29.   Once the cause is known, the National Transportation Safety Board will probably respond with some safety recommendations.