Rescue workers had collected 820 birds from the Gulf of Mexico oil spill, the majority of them already dead. The current spill p

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问题     Rescue workers had collected 820 birds from the Gulf of Mexico oil spill, the majority of them already dead. The current spill promises to be the largest in U. S. history,and as cleanup efforts stretch across the summer,it’s clear that more oiled birds will be found, stuck and suffering in the black sticky liquid. And as they do with every oil spill, rescue workers will go to great lengths to capture and clean the survivors hoping to restore them to their natural habitat.
    Is it worth the effort? Some scientists aren’t so sure. Because the stress of being captured and bathed is as significant as the horror of being immersed in oil, and because research suggests that many rescued birds die shortly after being released,some experts say euthanasia (安乐死) is a more humane option.
    Clean bird feathers repel water and regulate body temperature—dirty ones don’t. Oil in particular makes feathers heavier and diminishes their ability to trap air,which in turn makes birds more vulnerable to drowning, overheating and organ damage. Of course, being captured and cleaned is no picnic either. Some birds wind up returning to their destroyed habitats only to fall victim to the oil again. And those who manage to avoid a second oil bath suffer dramatically shortened life spans and lower reproductive success. Of the thousands of birds that were rescued from the Prestige oil spill off the coast of Spain in 2002, only 600 were released into the wild; most of the rest died after just a few days in captivity.
    However,bird rescuers say they have learned a lot about how to best help oil-soaked birds,and that therefore,survival rates stand to increase this time around. In the past,birds were cleaned right away, and volunteers often worked through the night bathing rescued birds. But now, captured birds are left to rest for a day or two before being cleaned, and only washed during the day, so as not to disrupt their cir-cadian (生理的) rhythms. But part of that increase may be due to greater selectivity on the part of rescuers. The workers do blood tests right in the field now and birds that are loaded with hydrocarbons (碳氢化合物 ) or don’t look like they’re going to make it are put down right away,rather than subjected to the stress of captivity and cleaning.
    And so far,while release rates may be improving,there is little evidence of better medium or long-term survival, especially for the more-difficult-to-save species. There still aren’t good biomedical proto-cols(协议) ,for repairing the internal organ damage. Nevertheless,rescue efforts will continue,in large part because the public demands that. Euthanasia is a difficult thing to do, especially for people who have built their lives around saving animals.
Why do the survival rates of oiled birds increase?

选项 A、Oiled birds are kept in warm water for one or two days.
B、Twice clean of the oiled birds in daytime are not permitted.
C、The rescuers often select the birds that are likely to survive.
D、Hydrocarbons are removed to rescue the oiled birds.

答案C

解析 事实细节题。定位句指出,存活率上升的一部分原因在于救援者的选择性更强了,通过验血,他们确定哪些鸟能被救活,而不能被救活的鸟马上会被丢掉。因此,C)“救援者通常会选择生存可能性较大的鸟”,符合题意,故为本题答案。A)“油污鸟被浸在温水中一两天”,原文提到的方法是在清洗之前,救援人员会让油污鸟休息一两天,选项错误,排除;B)“在白天清洗油污鸟两次是不被允许的”,原文只提到清洗工作应在白天进行,但并未提及清洗次数,排除;D)“清除碳氢化合物援救油污鸟”,原文只是说救援人员不会救碳氢化合物超标的油污鸟,并没有提到救助油污鸟的方法是清除碳氧化合物,排除。
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