Answer:
1. I have been buying a new pair of shoes.
2. Have you finished that book yet?
3. They have been eating fruit all afternoon, ever since they came from school.
4. I have read this book now, so you can have it back.
5. I have written eight pages already.
6. Your exam paper is completely blank! What have you been doing?
7. Oh, no! There's nothing to eat. My has eaten everything I left in the kitchen.
8. Oh, no! There's no wine to drink. They have drunk all the wine.
9. No wonder your eyes hurt. You have played computer games ever since you had your breakfast