CREATE TABLE table_42320 ("CERCLIS ID" TEXT, "Name" TEXT, "County" TEXT, "Proposed" TEXT, "Listed" TEXT, "Construction completed" TEXT, "Partially deleted" TEXT, "Deleted" TEXT)

When was construction completed that was listed on 09/21/1984 and a Deleted of 11/04/1999?
SELECT "Construction completed" FROM table_42320 WHERE "Listed" = '09/21/1984' AND "Deleted" = '11/04/1999'
SELECT "Construction completed" FROM "table_42320" WHERE "Deleted" = '11/04/1999' AND "Listed" = '09/21/1984'