21.   But many experts caution that such lenses do not make people see colors as people with normal vision do.

22.   But some pain experts cautioned that those studies may have limited value because they involved patients in controlled settings like hospitals rather than the public.

23.   But some sex-crime experts cautioned that Singleton was an anomaly in several respects.

24.   But some experts caution that the cause of the decline is unclear.

25.   But terrorism experts cautioned that the group might be trying to exaggerate its importance by taking responsibility for one of the most serious anti-American acts in years.

26.   But some outside experts caution that Clinton must do more.

27.   But the experts cautioned the public not to expect sudden success and stressed that it would take years, and millions of dollars, to complete such research.

28.   But the long-awaited plan could unwittingly plunge the Internet into chaos, experts cautioned.

29.   But some experts caution that a Republican turnaround is not guaranteed.

30.   But with yields at such a nadir and the next major rate move probably higher, experts caution against locking in a lot of money at these levels.