31.   Now that researchers know exactly how the genes can be activated, said Tilly, there is the potential taht they can be deactivated.

32.   Nor do researchers yet know the impact of testosterone replacement therapy on prostate disease or prostate cancer.

33.   Outbreaks, researchers know, come in cycles.

34.   Researchers already know that smokers are price-sensitive.

35.   Researchers also knew that each of three genes in a group known as the ABC genes could turn on the making of particular flower parts.

36.   Researchers do not know whether the supplements merely delay vision loss or whether they can postpone it indefinitely.

37.   Researchers do not know why the sexes respond differently to the drug.

38.   Researchers do not know why this happens, but it gives hope for extending the period when anti-AIDS drugs are effective.

39.   Researchers had long known that certain areas of the brain regulate specific psychological and physiological functions.

40.   Researchers have long known that HIV, which causes AIDS, can rapidly lose susceptibility to any drug in a given patient.