問題詳情

As recently as a decade ago, farms in the Midwest were commonly marred — atleast as a farmer would view it — by unruly patches of milkweed amid the neat rows ofemerging corn or soybeans.Not anymore. Fields are now planted with genetically modified corn and soybeansresistant to the herbicide Roundup, allowing farmers to spray the chemical to eradicateweeds, including milkweed. And while that sounds like good news for the farmers, agrowing number of scientists fear it is imperiling the monarch butterfly, 11spectacular migrations make it one of the most beloved of insects — “the Bambi of theinsect world,” as an entomologist once put it. Monarchs lay their eggs on milkweed, andtheir larvae eat it. While the evidence is still preliminary and disputed, experts like ChipTaylor say the growing use of genetically modified crops is threatening theorange-and-black butterfly by depriving it 12 its habitat.The major evidence that monarch populations are in decline comes from a newstudy showing a drop over the last 17 years of the area occupied by monarchs in centralMexico, where many of them spend the winter. The amount of land occupied by themonarchs is thought to be a proxy for their population size. “This is the first time wehave the data that we can analyze 13 that shows there’s a downward trend,” saidErnest H. Williams, a professor of biology at Hamilton College and an author of thestudy along with Dr. Taylor and others. The paper, published online by the journal InsectConservation and Diversity, 14 the decrease partly to the loss of milkweed fromuse of “Roundup Ready” crops. Other causes, it says, are the loss of milkweed to landdevelopment, illegal logging at the wintering sites in Mexico, and severe weather. Thestudy does not suggest the monarch 15 extinct. But it questions whether the annualmigration, the impetus for butterfly festivals around the United States and waves oftourism to Mexico, is sustainable.
11.
(A) whose
(B) which
(C) what
(D) where

參考答案

答案：A
難度：適中0.588235
統計：A(10),B(5),C(0),D(2),E(0)

內容推薦

內容推薦