Caffeine not only gives us a daily jump start,but new research suggests it also can strengthen long-term memory.
　　According to the US Food and Drug Administration,nearly 90 percent of people worldwide consume about 200 milligrams of caffeine each day.That's equivalent to about one strong cup of coffee a day.Writing in"Nature Neuroscience",Johns Hopkins University researchers say their findings show that caffeine strengthens certain memories for up t0 24 hours after being taken in.
　　"We've always known that caffeine has cognitive-enhancing effects(促智效果),but its,particular effects on strengthening memories and making them resistant to forgetting has never been examined in detail in humans,"said senior author of the paper Michael Yassa."We re-port for the first time a specific effect of caffeine on reducing forgetting over 24 hours."Conducting a double-blind trial,the researchers worked with a test group of people who didn't regularly consume caffeinated products.Five minutes after studying a series of images,the test subjects were given either a placebo(无效对照剂)or a 200-milligram caffeine tablet.
　　To check the caffeine levels of their test subjects,the research team took saliva samples(唾液样品)from them before they took their tablets and again one,three and 24 hours after-wards.
　　Both groups of test participants(those who took the placebo and those who took the caffeine tablet)were tested the following day to see if they could recognize the images they'd seen the previous day.
　　The test included showing the test subjects another series of images that included some new images,those that were shown the previous day,as well as other images that were similar,but not the same as those they had viewed earlier.
　　The researchers found that more members of the group who were given the caffeine tablets were able to correctly identify some of the new images as"similar"to previously viewed images rather than incorrectly identifying them as the same.
　　"We also know that caffeine is associated with health and longevity(长寿)and may havesome protective effects from cognitive decline like Alzheimer's disease(阿尔茨海默症)."said Yassa.
　　1、During the research,the researchers did the following things EXCEPT__.
　　A.giving the test subjects placebos or caffeine tablets
　　B.checking the caffeine levels of the test subjects
　　C.encouraging the test subjects to drink more coffee
　　D.showing the test subjects series of images
　　参考答案：C
　　参考解析：细节题。根据文章第二段the test subjects were given either a placebo(无效对照剂)or a 200-milligram caffeine tablet可知A是试验内容。根据文章第4段To check the caffeine levels of their test subjects,the research team took saliva samples(唾液样品)from them before they took their tablets and again one,three and 24 hours after-wards.可知B是试验的内容。根据Both groups of test participants(those who took the placebo and those who took the caffeine tablet)were tested the following day to see if they could recognize the images they'd seen the previous day.可知D项是试验内容。只有C项在文章里没有提及。
　　2、The purpose of the new research is__.
　　A.to survey how much caffeine people consume a day
　　B.to write the paper"Nature Neuroscience"
　　C.to prove caffeine has cognitive-enhancing effects
　　D.to examine caffeine's memory-strengthening effects in detail
　　参考答案：D
　　参考解析：推理题。根据文章第三段Conducting a double-blind trial,the researchers worked with a test group of people who didn't regularly consume caffeinated products.Five minutes after studying a series of images,the test subjects were given either a placebo(无效对照剂)or a 200-milligram caffeine tablet.可知这次试验只是为了检验咖啡因对于长期记忆的影响。故D正确。
　　3、What will the next part of the text possibly talk about?
　　A.Ways to achieve health and longevity.
　　B.The effects caffeine has on health.
　　C.The treatment for Alzheimer's disease.
　　D.The harmful effects of cognitive decline.
　　参考答案：B
　　参考解析：推理题。根据文章最后一段第一行"We also know that caffeine is associated with health and longevity(长寿)可知咖啡因对于人的健康也有影响，那么在下面一段一个展开讨论这个话题。故B正确。
　　4、How did the test subjects show the caffeine's memory-strengthening effects?
　　A.By recognizing images they'd seen the previous day.
　　B.By taking the caffeine tablets instead of placebos.
　　C.By identifying the new images as the same.
　　D.By telling the differences between new images.
　　参考答案：A
　　参考解析：推理题。根据文章倒数第二段The researchers found that more members of the group who were given the caffeine tablets were able to correctly identify some of the new images as"similar"to previously viewed images rather than incorrectly identifying them as the same.可知研究人员主要是通过让参加试验的人来辨认之前给他们看见的照片来检验咖啡因对人的长期记忆的影响的。故A正确。