单选题：Napping to a Healthier Heart?　　Researchers say they have dev

　　Napping to a Healthier Heart?
　　Researchers say they have developed a．simple test that can tell if a person with]heart disease is likely to suffer a heart attack．The test measures levels of a protein in the blood．The researchers say people with high levels of this protein are at high risk of heart attack。heart failure3 or stroke．
　　Kirsten Bibbins—Domingo of the University of California in San Francisco led the team．For about four years，they studied almost one thousand patients with heart disease．The researchers tested the heart disease patients for a Drotein called N31-proBNP．4 Patients with the highest levels were nearly eight times more likely than those with the lowest levels to have a heart attack，heart failure or stroke．
　　The researchers say the presence of high levels of the protein in the blood shows that the heart muscle is under pressure in some way．The study involved mostly men，so the researchers could not say for sure that the resuhs are also true。for women．They say the patients with the highest levels of NT—proBNP were older and had other problems like diabetes or high blood pressure．
　　Other researchers say more studies are needed to eonfilTn if knowing the protein levels of a heart patient should affeet that person’s treatment．They also would like to know if more aggressive treatment6 could reduce the patient’s chance of a heart attack or stroke．The study appeared in the Journal of the American Medical Association．7Could a little sleep during the middle of the day reduce the risk of a heart attack?An unrelated studv earlier this month：in the Archives of Internal Medicine8 suggests that the answer may be yes．In countri’es like the United States．
　　afternoon naps are mostly for children．But they are common for adults in Mediterranean countries，And these countries generally have lower rates of heart disease．So seienhsts in the United States and Greece wondered if naps eould play a part．Twenty—three thousand healthy adults took part in the study．by Harvard University and the University of Athens．9 Those who took。thirty—min’ute naps three times a week had a thirty—seven percent lower risk of death from heart problems than people who did not take naps．
　　The researchers say napping may improve heart health by reducing stress They say the research suggests that naps are especially good for working men．But they say not enough female subjects died during the study to judge the benefits for women．
词汇：
nap n．vi．(白天)小睡，打盹；睡午觉
failure n．衰竭
stroke n．中风diabetes n．糖尿病
archive n．(常用复数)档案；档案室
Mediterranean aaj．地中海的
subject n．受实验者
注释：
1．Napping to a Healthier Heart?午睡可以使心脏更健康吗?to在这里表示达到某种结果或效果。
2．heart attack：心脏病发作
3．heart failure：心力衰竭
4．NT—proBNP：N端-脑型利钠肽原(或：N末端前脑利钠肽)。它是心肌中的一种压力指示因子，有望成为预测冠心病转归的生化标志物。
5．for sure：确实，毫无疑问地
6．aggressive treatment：损伤性治疗(aggressive原意是“有攻击性的，侵略的”)
7．American Medical Associ