31.   The existing system has proved a school for scandal in several counties.

32.   The first fare was a nickel, and the system proved an immediate financial success.

33.   The FEMA official, Tim Putprush, said he contacted the stations without White House guidance, but that the system proved unnecessary.

34.   The glass ceiling between women and the top job in school systems is proving one of the most difficult to shatter.

35.   The gyro stabilization system proved so steady that it has not significantly changed over the last three decades.

36.   The mayor would have done well, many say, to bite his tongue and let the system prove on its own that it can work.

37.   The system has proved nettlesome before.

38.   The system proved inaccurate.

39.   The system proved troublesome when I got off course.

40.   The system has proven amazingly resistant to changes or updates based on U.S. strategy or the international environment.