CREATE TABLE table_37437 ("Race" CLOB, "Length" CLOB, "Class" CLOB, "Circuit" CLOB, "Date" CLOB)

Which circuit was held on May 7 for 1 hour?
SELECT "Circuit" FROM table_37437 WHERE "Date" = 'may 7' AND "Length" = '1 hour'
SELECT "Circuit" FROM "table_37437" WHERE "Date" = 'may 7' AND "Length" = '1 hour'