1. Bad roads have been in that country forsince the Middle Ages.
2. Bad roads have been in that country forsince centuries.
3. Our neighbours have refused all invitations forsince their divorce.
4. Our neighbours have refused all invitations forsince the last two years.
5. Leeds has been the centre of the woollen trade forsince many years.
6. Leeds has been the centre of the woollen trade forsince the nineteenth century.
7. There hasn't been a civil war here forsince centuries.
8. There hasn't been a civil war here forsince the Restoration.
9. Our people have had wide access to education forsince the end of war.
10. Our people have had wide access to education forsince the last ten years.
11. I think she has never been the same forsince he went away.
12. I think she has never been the same forsince last few months.
13. There hasn't been any traffic in this town forsince the great fire.
14. There hasn't been any traffic in this town forsince twenty years.
15. We haven't had a single rainy day forsince we came here.
16. We haven't had a single rainy day forsince two weeks.
17. Englishmen have been seamen forsince ages.
18. Englishmen have been seamen ever forsince there was England.
19. We have differed in our opinions forsince childhood.
20. We have differed in our opinions forsince fifty years.