41.   But for Relkin and others, the most immediate ethical question is how to study people who had apo E tests done in connection with heart disease research.

42.   But he said that, in line with federal requirements, the test had been done within the last five years.

43.   But few tests have been done with such vehicles, which have only recently become popular, so nobody knows whether they pose a problem.

44.   But if performance-based tests are done right, Geller -- who specializes in transportation safety -- believes they are more effective than drug or alcohol tests.

45.   But the center did not record the stage of pregnancy at which the tests were done.

46.   But the law enforcement officials did not know how often the tests were done.

47.   But when engineers did the tests again recently, they did not find the chlorine isotope, raising the possibility of testing error.

48.   Christiane Ayotte, who heads the University of Quebec lab that did the test, said the only possible explanation was that he took steroids.

49.   Clyde Charles spent nine years trying to persuade the Louisiana courts to let him have a DNA test done.

50.   Corry said tests were being done to see if the nylon flock fibers at mill concentrations could be ignited by static electricity or an electrical spark.