41.  The main force behind the rapid spread of these shows is not artistic but financial.

42.  The main force behind the shift to bigger farms is the economies of scale.

43.  The main force driving up the number of insured people has been a national economic recovery, Sager said.

44.  The main force, however, would deploy several days after the signing of a formal peace accord in Paris.

45.  The main allied forces in the area of Bosnia where he lives are French.

46.  The main American force in Tuzla is a three-hour drive from Zenica, where the sight of an American soldier or journalist is still a novelty.

47.  The PRI, the other main force, will extract a high price for its backing.

48.  The Red Sox now point at economics as the main force pushing them toward a new stadium.

49.  The temperature variation from equator to pole is a main driving force in the circulation of the atmosphere and oceans.

50.  The two made up the main force on the Buffalo power play for eight years before they were traded.