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

### Instruction:
What were the air-dates of the episodes before episode 4 that had a BBC One weekly ranking of 6?

### Inputs:
table_name: table, columns: ['Episode No.', 'Airdate', 'Total Viewers', 'Share', 'BBC One Weekly Ranking']

### Response:
SELECT Airdate FROM table WHERE Episode No. < 4 AND BBC One Weekly Ranking = 6