41.   And if liquid water once existed on Venus and Mars, then it may have nourished primitive life forms that have since gone extinct.

42.   And if the ozone layer disappeared completely, plants and animals could not exist on land.

43.   And people wonder why racial tensions exist on American campuses!

44.   And it existed on several levels.

45.   And indeed, he hits just one key and the sound seems to exist on its own, forever in time and space, until finally he continues playing.

46.   And you can take a snapshot of the project as it exists on a particular day and archive it for future reference.

47.   Architecture, however, exists on the symbolic as well as the material plane.

48.   Another trouble spot exists on the offensive line.

49.   At that point, she says, very little general-interest material for Latinos existed on the Internet.

50.   At present no agreement exists on what sort of government might come to power if the radical Islamic Taliban were ousted.