Crossword Puzzle '-- have believed it?'

Clue: '-- have believed it?'

39th vice president (AGNEW with 5 letters)
39th Veep (AGNEW with 5 letters)
39th of 50 (NORTHDAKOTA with 11 letters)
39th V.P. (AGNEW with 5 letters)
America's 39th President (CARTER with 6 letters)
Favorite Hall of Famer of the 39th U.S. president? (GARYCARTER with 10 letters)
39th president of the United States (JIMMYCARTER with 11 letters)
It equals 0.3937 inch (CENTIMETER with 10 letters)
Super Bowl to be played in the year 3968, at the current rate (MMII with 4 letters)
Alma mater of the 39th Pres. (USNA with 4 letters)