SAT考试9月每日精选题40

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Critical Reading>Select an Answer

Building a road through wilderness certainly has avisible impact on local flora and fauna—you'rephysically paving over a slice of what was oncehabitat. But roads have less obvious effects, too.Like the introduction of traffic noise, which also takesa toll. "You can see an oil spill but you can't see a traffic noise spill. So convincing people thatit's important is a little more difficult," said Heidi Ware.

Ware is an ornithologist at the Intermountain Bird Observatory in Boise, Idaho. She and hercolleagues studied the reactions by birds to the sounds of vehicles. And they did it withoutpaving the great outdoors. Instead, they mounted 15 pairs of speakers on Douglas fir trees,along a ridge near Boise, and played traffic noise. They thus created what they call a "phantomroad" through the wilderness, which boosted local noise levels 10 decibels higher than those inthe surrounding forest.

Turns out just the sounds of traffic scared away a third of the area's usual avian visitors, andcut species diversity too. And birds of multiple species were not able to pack on as much fatto fuel their migrations, when they were forced to dine to the soundtrack of traffic.

Follow-up experiments in the lab found that, when it's noisy, birds spend a lot less time headdown, pecking at food, and a lot more time scanning their surroundings.

Ware says Yosemite, Glacier and Rocky Mountain National Parks all have roads that are busyenough to produce these effects. And, short of closing park roads to traffic, she says thingslike rubberized asphalt and lower speed limits could help cut the noise. "Glacier National Park isgoing to put up signs, that instead of showing your speed and preventing people fromspeeding, it's going to show how loud their car is on the road." Which, hopefully, will continueto encourage wilderness lovers to leave no trace—visible or audible.

The primary purpose of the second paragraph is to ____

(A) establish the credentials of researchers who conducted an experiment.

(B) present a hypothesis a group of researchers set out to investigate.

(C) identify the locations of the sites where a study was conducted.

(D) outline the methodology researchers used in a study.

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答案：D

解析：

Choice D is the best answer. In the second paragraph the author's main focus is on outlining the methods Ware and her colleagues used in their study. The author explains that the researchers used speakers to simulate a road that raised noise levels by 10 decibels in order to study birds' reactions to the noise.

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