21.   Although most of the convention has centered on partisan politics, Gore used his visit to bring Texas some federal bacon.

22.   Although the debate centered on the qualifications of Foster to be surgeon general, the political contest behind it was important.

23.   Among scientists, the enthusiasm centers on embryonic stem cell research.

24.   Among state and local governments, much of the concern appears to center on the proposed work requirements.

25.   Although most of the controversy at the conference centered on sexual and reproductive issues, the document addresses far more than how a women conducts her sex life.

26.   Amanda Sutphin, an archeologist for the landmarks commission, said that the most sensitive aspect of the project centers on human remains.

27.   An assured, contemplative first novel whose action, which centers on a Scottish father and his three sons, unfolds over the course of a decade.

28.   Among the many provisions likely to spark partisan debate, the more controversial could center on abortion and sex education.

29.   An assessment of the interpretation of the research will probably center on the fact that it is based largely on extrapolations back in time.

30.   Analytical news story trying to make sense of the conflicting global developments centered on the carnage in a small town in northwest Bosnia.