21.  Ms. Raab agrees with preservationists that the debate is not about saving distinguished architecture, heretofore the principal reason for landmarking.

22.  New herbicides have helped farmers control weeds, the principal reason for plowing.

23.  Now their principal reason for being here is France, not other writers.

24.  On Monday, Mikhailov had singled out the purported killing of the policemen as a principal reason for the start of the assault.

25.  Surveys also found that the environment was a principal reason voters had favored Democratic challengers over Republican incumbents in several close races for Congress last year.

26.  That audience, it turns out, is the principal reason many of the performers pay regular visits to the series.

27.  That is the principal reason we publish our opinions.

28.  The experiments have been cited as the principal reasons Glenn is going into space for the second time.

29.  The principal reason is a free tuition program used by almost every freshman at the university and paid for by proceeds from the Georgia lottery.

30.  The principal reason we entered into this was to put that allegation, which has dogged us for decades, behind us.