Here are the sentences rephrased as requested:

1. I have received his letter **for** a week.
- I have had his letter for a week.

2. I have known her **for** several years.
- I have known her for several years.

3. He has owned the car **since** last month.
- He has had the car since last month.

4. They have lived in this village **for** a decade.
- They have been living in this village for a decade.

5. She has worked at the company **for** five years.
- She has been working at the company for five years.

6. John and Mary have attended the school **since** the beginning of the year.
- John and Mary have been attending the school since the beginning of the year.

7. We have had the new puppy **for** a week.
- We have had the new puppy for a week.

8. He has studied Spanish **for** two years.
- He has been studying Spanish for two years.

9. I have eaten dinner **for** an hour.
- I have been eating dinner for an hour.

10. They have moved to a new house **for** 2 weeks.
- They have been living in a new house for 2 weeks.

11. They have known the truth **for** 3 days.
- They have known the truth for 3 days.

12. Kelly has bought that dress **for** 3 weeks.
- Kelly has had that dress for 3 weeks.

13. This painting has been hung in the museum **for** 10 years.
- This painting has been in the museum for 10 years.

14. The treasure has been hidden **for** decades.
- The treasure has been hidden for decades.

15. The package has been delivered **since** last month.
- The package has been with us since last month.