21.   The Caspian basin, which is rich in oil and gas reserves, is central to his new foreign policy doctrine.

22.   The extremes of the anti-war protest movement, which was very central to the film itself, had had their day.

23.   The following incident, which is central to the plot, demonstrates their different positions.

24.   The idea of questioning is central to the chapters on reading, note making and documentary evidence.

25.   The idea that maximizing personal consumption is central to individual welfare is less than two hundred years old.

26.   The principle that justice should, as far as possible, be open is central to our system of criminal justice.

27.   The query formulation is central to a successful outcome.

28.   The right to vote is central to our democratic system of government.

29.   The sense of an unbroken participatory field of reality was central to the primal mind as well.