Has Martin been to India?
Yes, he has. Martin has been to India.

  Have Nicholas and Claire met?
Yes, they have. Nicholas and Claire have met.

  Have you met your new boss?
No, I haven't. I haven't met my new boss.

  Have they finished dinner?
No, they haven't. They haven't finished dinner.

  Have you bought some/any milk?
No, I haven't. I haven't bought any milk.

  Has Nicholas been to Dallas?
Yes, he has. Nicholas has been to Dallas.