CREATE TABLE table_4847 ("Player" TEXT, "Nationality" TEXT, "Position" TEXT, "From" FLOAT, "School/Country" TEXT)

Who is the player in the center position from 2006 with nationality of the United States?
SELECT "Player" FROM table_4847 WHERE "Nationality" = 'united states' AND "Position" = 'center' AND "From" = '2006'
SELECT "Player" FROM "table_4847" WHERE "From" = '2006' AND "Nationality" = 'united states' AND "Position" = 'center'