user: Question: In what county is the entry that has a Construction Completed date of 07/19/2000 and a Listed date of 09/21/1984 located?
Columns: ['CERCLIS ID', 'Name', 'County', 'Proposed', 'Listed', 'Construction completed', 'Partially deleted', 'Deleted']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['AL6210020008', 'Alabama Army Ammunition Plant', 'Talladega', '10/15/1984', '07/22/1987', '–', '–', '–']
SQL:

assistant: SELECT "County" FROM "Table" WHERE "Listed" = '09/21/1984' AND "Construction completed" = '07/19/2000';