21.   Upland valleys present additional problems because of their often numerous isolated field barns - sometimes one for each hay meadow.

22.   When the model is at some height and still moving forwards it will present no problems.

23.   Large classes present great problems to many teachers.

24.   This presents a problem for many financial consumers.

25.   The semi-circular arch presents great problems in vaulting a church.

26.   A system that presents ethical problems to the experimenter is the demographic system.

27.   Inserting and deleting records also presents a problem.

28.   Deleting a record may also present problems.

29.   Random access files can present problems mainly because an appropriate randomising formula is often difficult to construct.

30.   As we saw, the necessity for overflow records presents problems with index sequential files.