3. Form question tags.

Solution:

• 1. You haven't seen this thriller, have you? (Negative statement requires a positive tag).
• 2. He is never late, is he? (Negative statement 'never' requires a positive tag).
• 3. She lives in that cosy cottage, doesn't she? (Positive statement requires a negative tag).
• 4. They will come to the party, won't they? (Positive statement requires a negative tag).
• 5. It was a great adventure, wasn't it? (Positive statement requires a negative tag).

Final Answer: 1. have you, 2. is he, 3. doesn't she, 4. won't they, 5. wasn't it