21.   The education gap is real, and Borjas is probably right in concluding that it will take several generations to erase.

22.   The new Sony machine will not process text or calculate a budget, but it will take a generation of youngsters to the threshhold of virtual reality.

23.   The Middle Ages are alive and well-resurrected in the sort of monument that used to take medieval generations of artisans and craftsmen to raise in Europe.

24.   They are fragile, need protection, and will take generations to develop.

25.   They have taken generations of Kings along country roads, across the continent, over oceans and beyond racial barriers.

26.   Those hazards are often man-made toxic chemicals that enter the atmosphere and can take many generations to decompose.

27.   But he also said the fight to end corruption would be a marathon effort that could take generations.

28.   But it may take several generations of laboratory-bred pigs over many years to weed out the genes that trigger immune-system rejection.

29.   But corresponding sociopolitical changes still take several generations.

30.   Environmental officials have identified the problems, but fixing them could take generations and will require balancing competing demands.