1. Mark the boundary with pegs.

2. The boundary questions still remain unsettled.

3. The river is the boundary between the two countries.

4. Boundary walls have had to be shored up.

5. The mountain is the boundary between the two countries.

6. The river forms the boundary.

7. The Ural mountains mark the boundary between Europe and Asia.

8. The fence marks the boundary between my land and hers.

9. The Mississippi River forms a natural boundary between Iowa and Illinois.

10. Establish which boundary hedges are yours, and which belong to a neighbour.

11. We continued along the southern boundary of the country.

12. The duke perambulated the boundary of his estate.

13. The boundary changes were denounced as blatant gerrymandering.

14. This film blurs the line/distinction/boundary between reality and fantasy.

15. The boundary was marked with a dotted line.

16. The ball ran to the boundary.

17. The state has a boundary with Ontario.

18. The boundary treaty was negotiated between the two countries.

19. The batsman stroked the ball effortlessly to the boundary.

20. He cut the ball to the boundary.

21. We've just crossed the boundary into Sussex.

22. We had to stop at the boundary.

23. They drove across the boundary.

24. The boundary was fixed just south of the farm.

25. The river forms the county boundary.

26. The lane is the boundary of our land.

27. The stream curves round to mark the boundary of his property.

28. A blind man who leans against a wall imagines that it's the boundary of the world. 

29. The ball rose in a high arc and fell behind the boundary line.

30. The ball was caught by a fielder standing just inside the boundary.