1. the official spoke on condition of anonymity because he is not authorized to speak

2. on either side of the river

3. on the bottom of the page

4. on the top of the rock

5. in a blog post on the website

6. to get their hands on paper

7. on the surface of the Sun

8. to keep an eye on him

9. on both sides of the river

10. on the side of the road

11. the success will depend on the cooperation of its partners

12. with a special focus on fiscal issues

13. based on a number of factors

14. on the streets of

15. on the grounds that

16. on its way to

17. a significant impact on

18. on a series of

19. arrested on suspicion of

20. on the way to

21. keep a close eye on

22. in a report on

23. on the eve of

24. on the issue of

25. have an impact on

26. declined to comment on

27. on the floor of

28. on the ground in

29. on the same day

30. on the edge of