user: Question: What is the nhl team for the position Centre and nationality United States?
Columns: ['Pick #', 'Player', 'Position', 'Nationality', 'NHL team', 'College/junior/club team']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [103.0, 'Patrick Emond', 'Centre', 'Canada', 'Pittsburgh Penguins', 'Hull Olympiques (QMJHL)']
SQL:

assistant: SELECT "NHL team" FROM "Table" WHERE "Position" = 'Centre' AND "Nationality" = 'United States';