题型：阅读理解 题类：常考题 难易度：普通
福建省厦门市2020届高中毕业班英语第二次质量检查（6月）试卷
In habitats across the planet, animals periodically drop everything to walk, fly or swim to a new place. Wildlife such as whales and geese learn migration (迁移) paths by following heir parents. Others, including small songbirds, gain the distance and direction of their migration within their genetic (遗传的) code And some animals use a combination of genetics and culture to guide their migration.
Another group of migrators does not quite fit either model, and researchers have only recently started to figure out how they find their way. Take the Cory's shearwater, an oceangoing sea bird that migrates over the Atlantic every year. The young do not migrate with their parents, so culture cannot explain their journeys. And the exact paths vary wildly from individual to individual, making genetics equally unlikely.
Cory's shearwaters are long-lived, rarely producing young successfully before age nine. This leaves an opening for learning and practice to develop their migration patterns. Researchers call this the "exploration-refinement", and until now it has been hypothetical (假设的) because of difficulties in tracking migratory animals' movements.
But a team of researchers has done that by attaching small geolocators to more than 150 of the birds aged four to nine. They found that younger birds traveled longer distances, for longer periods, and had more diverse paths than older birds. "We finally have evidence of the "exploration-refinement" for migratory birds," says Letizia Campioni, who led the study. Younger Cory's shearwaters are able to fly just as fast as the adults- but they do not, suggesting that the young do more exploring, which gradually fades as they mature and settle into a preferred course.
Although it may seem less efficient than other strategies, "exploration refinement could be beneficial to birds and other organisms in a rapidly changing world due to unpredictable man-made changes," says Barbara Frei. "It might be safer to repeat a behavior that was recently successful than to rely on patterns that were perfected long ago but might no longer be safe."
The main cause of death and disability in the US
Stroke (中风) is the main cause of death and disability in the United States. Every 45 seconds, someone in America has a stroke. {#blank#}1{#/blank#} It is the nation's third leading cause of death, ranking behind diseases of the heart and all forms of cancer. The following is something more about stroke.
Definition and description of a stroke
Stroke is a type of cardiovascular disease. It affects the arteries(动脉) leading to and within the brain. A stroke occurs when a blood vessel（血管） that carries oxygen and nutrients to the brain is either blocked by a clot or bursts. {#blank#}2{#/blank#} So stroke forms.
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The American Stroke Association has identified several factors (因素) that increase the risk of stroke. The more risk factors a person has, the greater the chance that he or she will have a stroke. Some of these you can't control, such as increasing age, family health history, race, and previous stroke. {#blank#}4{#/blank#} Factors resulting from lifestyle or environment can be improved with a healthcare provider's help.
Breakthroughs in treatment
{#blank#}5{#/blank#} In fact, about 600,000 people have strokes every year. For many years, there was no hope for those suffering a stroke. However, recent breakthroughs have led to new treatments. For the treatments to work, the person must get to a hospital immediately.
A. Risk factors of a stroke. B .Warning signs of a stroke. C. Every 3.1 minutes, someone dies of one. D. A stroke can happen to anyone at any moment. E. But you can change or treat other risk factors to lower your risk. F. When that happens, part of the brain cannot get the blood and oxygen it needs. G .The more common kind of stroke is caused by a blood clot that blocks a blood vessel in the brain. |
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