user: Question: What is the extra when the result is 4th at the NCAA Championships?
Columns: ['Year', 'Tournament', 'Venue', 'Discipline', 'Result', 'Extra']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [2008.0, 'Summer Olympics', 'Beijing , China', '400m', 'SF', '44.88 s (NR)']
SQL:

assistant: SELECT "Extra" FROM "Table" WHERE "Result" = '4th' AND "Tournament" = 'NCAA Championships';