問題詳情

第26至30題爲題組
        As recently as a decade ago，farms in the Midwest were commonly marred — at least as a farmer would view it — by unruly patches of milkweed amid the neat rows of emerging com or soybeans.
        Not anymore. Fields are now planted with genetically modified com and soybeans resistant to the herbicide Roundup, allowing farmers to spray the chemical to eradicate weeds, including milkweed. And while that sounds like good news for the farmers, a growing number of scientists fear it is imperiling the monarch butterfly,    26    spectacular migrations make it one of the most beloved of insects — ”the Bambi of the insect world," as an entomologist once put it. Monarchs lay their eggs on milkweed, and their larvae eat it. While the evidence is still preliminary and disputed, experts like Chip Taylor say the growing use of genetically modified crops is threatening the orange-and-black butterfly by depriving it    27    habitat.
        The major evidence that monarch populations are in decline comes from a new study showing a drop over the last 17 years of the area occupied by monarchs in central Mexico, where many of them spend the winter. The amount of land occupied by the monarchs is thought to be a proxy for their population size.
        ”This is the first time we have the data that we can analyze    28    that shows there's a downward trend," said Ernest H. Williams, a professor of biology at Hamilton College and an author of the study along with Dr. Taylor and others. The paper, published online by the journal Insect Conservation andDiversity,    29    the decrease partly to the loss of milkweed from use of "Roundup Ready" crops. Other causes, it says, are the loss of milkweed to land development, illegal logging at the wintering sites in Mexico, and severe weather.
        The study does not suggest the monarch    30    extinct. But it questions whether the annual migration, the impetus for butterfly festivals around the United States and waves of tourism to Mexico, is sustainable.

26.
(A) whose
(B) which
(C) what
(D) where

參考答案

答案：A
難度：適中0.4
統計：A(4),B(3),C(2),D(1),E(0)

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