CREATE TABLE table_12031 ("Race" TEXT, "Length" TEXT, "Class" TEXT, "Circuit" TEXT, "Date" TEXT)

What circuit was on June 1 with a class of both?
SELECT "Circuit" FROM table_12031 WHERE "Class" = 'both' AND "Date" = 'june 1'
SELECT "Circuit" FROM "table_12031" WHERE "Class" = 'both' AND "Date" = 'june 1'