2014考研英語(yǔ)復(fù)習(xí)：模擬試題之新題型專項(xiàng)練習(xí)(五十八)_跨考網(wǎng)

　　2014考研英語(yǔ)復(fù)習(xí)：模擬試題之新題型專項(xiàng)練習(xí)(五十八)

　　Part B

　　Directions:

　　In the following article, some sentences have been removed. For Questions 41—45, choose the most suitable one from the list A—G to fit into each of the numbered blank. There are two extra choices, which do not fit in any of the gaps.

　　Even some ardent conservationists acknowledge that the diversity of life on Earth cannot be fully sustained as human populations expand use more resources nudge the climate and move weedlike pests and predators from place to place.

　　Given that some losses are inevitable, the debate among many experts has shifted to an uncomfortable subject—what level of loss is acceptable. The discussion is taking place at both the local and global levels.41)______________________________. And as global biodiversity diminishes, is it a valid fallback strategy to bank organisms and genes in zoos, DNA banks or the like, or does this simply justify more habitat destruction? 42)_________________________________________. Some conservation groups have strenuously avoided or even attacked such calculations and strategies. They say there is no safe diminution of habitat as long as human understanding of ecology is as sketchy as it is a fallback strategy is unthinkable. Furthermore banking nature in a deep freeze or database of gene sequences cannot capture context. 43)_____________________. On the other side of the debate those considering what the smallest viable habitats are or how to expand archives as an insurance policy say that recent trends have proved that old conservation strategies are no longer sufficient. 44)_____________________________.

　　Twenty four years ago Dr. Thomas E. Lovejoy and other biologists began a remarkable experiment on the fast eroding fringe of rain forest near the Brazilian city of Manaus. They established 11 forest tracts ranging from 2.5 to 250 acres each surrounded by an isolating sea of pasture similar to what is advancing around most other tropical forests. Among the many findings an analysis published last week on birds in the lower layers of greenery found that it would take a fragment measuring at least 2 500 acres—10 times as large as the biggest one in the experiment—to prevent a decline of 50 percent in those bird varieties in just 15 years or so.

　　45)____________________________________________________________.