41.   The systems have also proven useful in treating the lasting shock caused by violent wartime experiences.

42.   The transition will be easier if the communication system proves to be effective.

43.   These systems may prove to be simpler to program and thus gain acceptance more quickly.

44.   This system has proved viable for a wide variety of reasons, and players in baseball and hockey should probably take note.

45.   What prompted the government to make the proposal was that the justice system has proved unable to judge so many people.

46.   Wilson reported last month that the system had proved successful in mice and in rhesus monkeys.

47.   A transitional system proved too flawed.

48.   Again, the system proved inflexible.

49.   But the system proved unsatisfactory to some of the plaintiffs and was considered of questionable legality under precedents set by the U.S. Supreme Court.

50.   Call it unusual, but after all these years, the system has proven to be a success.