1. Have they eaten spaghetti?
No, they haven't but they've eaten some pasta.
2. How much cities has she visited already?
She's visited three countries.
3. What languages have you studied?
We've studied French and Englisch
4. Have you met him?
No, I haven't met him.
5. Has he seen your homework?
Yes, he's seen it?
6. Have you traveled by train?
No, but I've travelled by bus