GRE作文范例4

GRE作文范例4 Topic The following is a letter to the editor of an environmental magazine "The decline in

GRE作文范例4 Topic The following is aletter to the editor of an environmental magazine "The decline in the numbers of amphibians worldwide clearly indicates the global pollution of water and air. Two studies of amphibians in Yosemite National Park in California confirm my conclusion. In 1915 there were seven species of amphibians in the park, and there were abundant numbers of each species. However, in 1992 there were only four species of amphibians observed in the park, and the numbers of each species were drastically reduced. The decline in Yosemite has been blamed on the introduction of trout into the park's waters, which began in 1920 (trout are known to eat amphibian eggs). But the introduction of trout cannot be the real reason for the Yosemite decline because it does not explain the worldwide decline." Sample Essay In this argument, the writer of the letter concludes that global pollution of water and air has caused adecline in the number of amphibians worldwide. To support his or her conclusion, the writer cites the results of two studies, seventy-five years apart, that purportedly show that the number of amphibians in one park in California, Yosemite National Park, have drastically declined. Additionally, the