Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
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?

### Inputs:
table_name: table, columns: ['CERCLIS ID', 'Name', 'County', 'Proposed', 'Listed', 'Construction completed', 'Partially deleted', 'Deleted']

### Response:
SELECT County FROM table WHERE Listed = 09/21/1984 AND Construction completed = 07/19/2000