鼠穴 都没有遇到什么机经唉。阴险题目不少 In planning for a trip, Joan estimated both the distance ofthe trip, in miles, and her average speed, in miles per hour. She accurately divided her estimated distanceby her estimated average speed to obtain an estimate for the time, in hours,that the trip would take. Was herestimate within 0.5hour of the actual time that the trip took? (1) Joan’s estimate for the distance was within 5 miles of the actualdistance. (2) Joan’s estimate for her average speed waswithin 10 miles per hour of her actual average speed. Gwd原题，答案E
楼主，请看下这是不是你考的那篇songbird文章 第二段：A few years ago, Jarvis and his colleagues made the surprising discovery that when a songbird, parrot or hummingbird is producing its learned vocalization, a set of seven similar structures in the birds’ brains become active. The finding was unexpected because the three avian groups are only distantly related to one another. At the same time, they are closely related to other birds that are not vocal learners. Flycatchers, for example, belong to the same order as songbirds—Passeriformes—yet no flycatcher species tested so far displays the trait. One possible explanation, says Jarvis, is that the three groups of vocal learning birds had a common ancestor that possessed the skill. “But this means there would have been multiple losses of the ability over time, a sort of mass extinction of vocal learning,” he says. Another hypothesis is that vocal learners evolved similar brain structures independently over the last 65 million years, much the same way that birds and bats separately evolved wings that turned out to be so much alike.
第三段：Discoveries about the human brain support this latter hypothesis. Scientists conducting imaging studies have found that when people speak, parts of their brains’ cerebrums that are similar to those of vocalizing songbirds, parrots and hummingbirds become active. They’ve also found that the same neural pathways are damaged in people who have lost the ability to speak due to injury or stroke. Jarvis now believes that vocal learning most likely developed independently in humans and the three bird groups (as well as in other learners whose brains have not been studied)—yet it arose from a pre-existing brain system, probably shared by all vertebrates, that controls learning to move.
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发表于 2011-9-27 22:26:17
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