21.   His health problems forced him to abandon his studies for now.

22.   His back problems have forced coaches to use him sparingly and in strategic spots.

23.   It was the second time a software problem had forced a delay in the ground tests.

24.   Its economic problems could force the regime to moderate its foreign policy and encourage more trading with the West.

25.   It was the second time in four days that hydraulic problems had forced a Sea Knight to make an emergency landing in California.

26.   Later in the decade, a sinus problem forced Delahoussaye to cut back on his schedule, in part because it made air travel untenable.

27.   Mechanical and electronic problems forced Jones and Filo to spend the time struggling to make the dog work.

28.   Meanwhile, water problems are forcing change on communities where growth has outpaced planning.

29.   Prolonged legal problems could force it to raise prices, however, a fact that Cooley pointed out last week in New York.

30.   Recent days have seen a wave of speculation that her fund-raising problems would soon force her to drop out of the race.