11.   But once researchers know the fungi can have sex, the picture becomes infinitely more complex and difficult.

12.   But researchers do know the fungus that causes Valley fever grows rapidly after it rains.

13.   But researchers do not know exactly how much cocaine must be used, or over how long a period, in order for the heart muscle to be damaged.

14.   But suicide researchers have known for a century that more people kill themselves in the warm weather months.

15.   But the data, researchers know, has not entirely persuaded the public.

16.   But until now researchers did not know the extent to which such problems affected surgical patients generally.

17.   Cocaine, researchers have long known, attaches to dopamine, which takes the cocaine to portions of the brain that provide the euphoria.

18.   Field researchers now know that coyotes hunting in concert can and often do bring down animals as large as adult deer.

19.   Few researchers knew that to watch the spawn meant staying up until the Jay Leno hour.

20.   Fortunately, researchers know more than ever about effective strategies for reducing anxiety.