Thousands of people around the globe step outside to gaze at their night sky. On a clear night, with no clouds, moonlight, or artificial lights to block the view, people can see more than 14,000 stars in the sky, says Dennis Ward, an astronomer with the University Corporation for Atmospheric Research (UCAR) in Boulder, Colo1. But when people are surrounded by city lights, he says, they're lucky to see 150 stars.

　　If you've ever driven toward a big city at night and seen its glow from a great distance, you've witnessed light pollution. It occurs when light from streetlights, office buildings, signs, and other sources streams into space and illuminates the night sky. This haze of light makes many stars invisible to people on Earth. Even at night, big cities like New York glow from light pollution, making stargazing2 difficult.

　　Dust and particles of pollution from factories and industries worsen the effects of light pollution. "If one city has a lot more light pollution than another," Ward says, "that city will suffer the effects of light pollution on a much greater scale. "

　　Hazy skies also make it far more difficult for astronomers to do their jobs.

　　Cities are getting larger. Suburbs are growing in once dark, rural areas. Light from all this new development is increasingly obscuring the faint light given off by distant stars. And if scientists can't locate these objects, they can't learn more about them.

　　Light pollution doesn't only affect star visibility. It can harm wildlife too. It's clear that artificial light can attract animals, making them go off course3. There's increasing evidence, for example, that migrating birds use sunsets and sunrises to help find their way, says Sydney Gauthreaux Jr., a scientist at Clemson University in South Carolina. "When light occurs at night," he says, "it has a very disruptive influence. " Sometimes birds fly into lighted towers, high-rises, and cables from radio and television towers. Experts estimate that millions of birds die this way every year.

　　词汇:

　　astronomer n. 天文学家 migrate v.迁移，迁徒

　　Illuminate v. 照明，照亮 disruptive adj.扰乱性的

　　haze n.薄雾 obscure v.使变模糊

　　faint adj.微弱的，暗淡的

　　注释：

　　1. University Corporation for Atmospheric Research (UCAR) : 大学大气研究社团，于1960年在美国科罗拉多州(Colorad0，缩写为Col0.)的玻尔(Boulder)市成立。该社团是一个由国内外大学组成的非营利性协会，致力于大气周围的空气和气候变化研究。

　　2. stargazing : 该词是个合成词，由star和gaze+in9组成，在此意为：观望星星。

　　3 making them go off course: 使它们偏离飞行路线。course：路线。

　　练习：

　　1. When can people see 14,000 stars?

　　A) When they have a fairly good telescope.

　　B) When they are in a large city.

　　C) When the night sky is clear of clouds, moonlight and artificial lights.

　　D) When the night sky is without haze and fog.

　　2. Which of the following statements is NOT related to light pollution?

　　A) A haze of light is formed from artificial lights such as streetlights and building lights.

　　B) Lights from different sources in the city stream into space and illuminate the night sky.

　　C) The night sky is illuminated by the lights from big glowing cities in the night.

　　D) Stargazing becomes difficult because there is a layer of haze in the air.

　　3. Does the writer think growing cities affect astronomers' work? Why does he think so?

　　A) Yes. Because the once dark rural areas are polluted by lights.

　　B) No. Because they can still see stars in rural areas.

　　C) Yes. Because rural areas are not a good place for astronomers to study stars.

　　D) No. Because faint light given off by stars can still be seen on a clear night.

　　4. How does light pollution affect wildlife? Which of the following is NOT correct?

　　A) Animals may go off course due to the attraction of artificial lights.

　　B) Animals might be attracted by artificial lights to go into cities.

　　C) Artificial lights at night may make migrating birds lose their way.

　　D) Attracted by artificial lights, birds fly into lighted buildings.

　　5. Which of the following is closest in meaning to the title "Light Night, Dark Stars"?

　　A) The night sky is light colored and stars are black.

　　B) Lights appear at night and stars are seen in the dark.

　　C) City lights illuminate the night sky and make stars invisible.

　　D) City lights at night illuminate stars in the sky.

答案与题解：

　　1.C 第一段的第一句提供了答案。在没有云，没有月光，没有人造光源的情况下，可以看见14，000颗星星。

　　2.D A、B、C所述内容均可在第二段中找到。D所表达的意思不符合原文，因为a layer of

　　haze in the air的意思是“空气中有一层薄雾”。

　　3.A 答案在第五段中可以找到。随着城市规模的扩大，曾经黑灯瞎火的乡村逐渐变成了市郊，那里的灯火使科学家无法观测到星体发出的微弱光芒。

　　4.B 第六段最后三句告诉我们人造光源会误导动物而致使它们迷路，但却没有说会将它们引进城市。

　　5.C 题目的意思是：城市灯火通明的夜晚使星星失去光泽。

　　Hair Detectives

　　Scientists have found a way to use hair to figure out where a person is from and where that person has been. The finding could help solve crimes, among other useful applications.

　　Water is central to the new technique. Our bodies break water down into its parts: hydrogen and oxygen. Atoms of these two elements end up in our tissues and hair.

　　But not all water is the same. Hydrogen and oxygen atoms can vary in how much they weigh. Different forms of a single element are called isotopes. And depending on where you live, tap Water1 contains unique proportions of the heavier and lighter isotopes of hydrogen and oxygen.

　　Might hair record these watery quirks2? That's what James R. Ehleringer, an environmental scientist at the University of Utah in Salt Lake City3, wondered.

　　To find out, he and his colleagues collected hair from barbers and hair stylists in 65 cities in 18 states across the United States. The researchers assumed that the hair they collected came from people who lived in the area.

　　Even though people drink a lot of bottled water these days, the scientists found that hair overwhelmingly reflected the concentrations4of hydrogen and oxygen isotopes in local tap water. That's probably because people usually cook their food in the local water. What's more, most of the other liquids people drink including milk and soft drinks contain large amounts of water that also come from sources within their region.

　　Scientists already knew how the composition of water varies throughout the country. Ehleringer and colleagues combined that information with their results to predict the composition of hair in people from different regions. One hair sample used in Ehleringer's study came from a man who had recently moved from Beijing, China, to Salt Lake City. As his hair grew, it reflected his change in location.

　　The new technique can't point to exactly where a person is from, because similar types of water appear in different regions that span a broad area. But authorities can now use the information to analyze hair samples from criminals or crime victims and narrow their search for clues.

　　词汇：

　　hydrogen n. 氢 overwhelmingly adv. 压倒性

　　Atom n. 原子 Isotope n. 同位素

　　span v. 跨越 Quirk n. 古怪举动;怪僻

　　clue n. 线索 Stylist n. 发型师

　　注释：

　　1. tap water: 自来水，管道供水

　　2. watery quirks: 水的奇特性质。quirk的含义是“an peculiar or unexpected behavioral habit”(古怪的不可预测的行为和事情)。

　　3. University of Utah in Salt Lake City: (美国)盐湖城的犹他大学

　　4. concentrations: 浓度;含量

　　练习:

　　1. What does the writer say about tap water? Which of the following is NOT correct?

　　A) Tap water reflects the concentrations of hydrogen and oxygen isotopes in different regions.

　　B) Tap water is a kind of soft drink in the United States.

　　C) Tap water contains unique proportions of isotopes of hydrogen and oxygen.

　　D) Tap water is used to cook food.

2. James R. Ehleringer tried to find out

　　A) if our bodies break water down into its parts.

　　B) if it is possible to collect hair samples across the country.

　　C) if tap water contains unique proportions of isotopes of hydrogen and oxygen.

　　D) if the composition of hair can indicate exactly where people are from.

　　3. Which of the following statements is meant by the writer?

　　A) Ehleringer was successful in his research.

　　B) Ehleringer failed in his research.

　　C) Ehleringer can be a successful detective.

　　D) Ehleringer's research proved successful in China.

　　4. What does the last paragraph tell you?

　　A) The new technique can tell precisely where a person lives.

　　B) Water supplied in different regions all come from the same source.

　　C) Types of water used in different regions provide useful information for the police.

　　D) Hair samples provide the most important clues to identify crimes.

　　5. Which of the following is closest in meaning to the title?

　　A) Human hair may help detectives to solve crimes.

　　B) Animal hair may help detectives to solve crimes.

　　C) Detectives watch hairy criminals closely.

　　D) Most detectives are hair specialists.

　　答案与题解：

　　1.B第三段和第六段谈到tap water。A、C、D均是文中提到的内容。8是错误的，因为文章第六段说，我们饮用的牛奶和软饮料都含有大量水分，而没有说tap water是软饮料。

　　2.C第四段的问句针对第三段的内容。these watery quirks指的是上段中的unique

　　proportions of the heavier and lighter isotopes of hydrogen and oxygen。所以C是正确答案。

　　3.A第六段和第七段提供了答案。科学家发现头发能反映出当地自来水中氢、氧同位素的含量;科学家也已经研究出不同地区水成分是不同的，并且在此基础上来确定来自不同地区的人的头发成分。

　　4.C选项A、B、D与原文均有出入。尽管在一个较大的范围内，人们使用成分较为相同的水，但是水的成分组成提供的信息可以帮助官方缩小破案线索范围。

　　5.A题目的意思是：人的头发可以帮助侦探破案。

　　Mind-reading1 Machine

　　A team of researchers in California has developed a way to predict what kinds of objects people are looking at by scanning what's happening in their brains.

　　When you look at something, your eyes send a signal about that object to your brain. Different regions of the brain process the information your eyes send. Cells in your brain called neurons are responsible for this processing.

　　The fMRI (functional Magnetic Resonance Imaging ) 2 brain scans could generally match electrical activity in the brain to the basic shape of a picture that someone was looking at.

　　Like cells anywhere else in your body, active neurons use oxygen. Blood brings oxygen to the neurons, and the more active a neuron is, the more oxygen it will consume. The more active a region of the brain, the more active its neurons, and in turn, the more blood will travel to that region. And by using fMRI, scientists can visualize3 which parts of the brain receive more oxygen-rich blood--and therefore, which parts are working to process information.

　　An fMRI machine is a device that scans the brain and measures changes in blood flow to the brain. The technology shows researchers how brain activity changes when a person thinks, looks at something, or carries out an activity like speaking or reading. By highlighting the areas of the brain at work when a person looks at different images, fMRI may help scientists determine specific patterns of brain activity associated with different kinds of images.

　　The California researchers tested brain activity by having two volunteers view hundreds of pictures of everyday objects, like people, animals, and fruits. The scientists used an fMRI machine to record the volunteers' brain activity with each photograph they looked at. Different objects caused different regions of the volunteers' brains to light up on the scan, indicating activity. The scientists used this information to build a model to predict how the brain might respond to any image the eyes see.

　　In a second test, the scientists asked the volunteers to look at 120 new pictures. Like before, their brains were scanned every time they looked at a new image. This time, the scientists used their model to match the fMRI scans to the image. For example, if a scan in the second test showed the same pattern of brain activity that was strongly related to pictures of apples in the first test, their model would have predicted the volunteers were looking at apples.

词汇：

　　scan v. &n. 扫描 visualize v. 使可见;设想

　　neuron n. 神经元

　　注释:

　　1. Mind-reading: 能读出(猜出)人的想法的。mind-read: 可做动词，如，As a successful

　　salesman, he is able to mind-read his customers.

　　2. FMRI (functional Magnetic Resonance Imaging) : 功能性磁振造影。这是一种新兴的神经影像学方式，其原理是利用磁振造影来测量神经元活动所引发之血液动力的改变。

　　3. visualize: 意为make(something)visible to the eye，即“使可见，使显现”。

　　练习:

　　1. What is responsible for processing the information sent by your eyes?

　　A)A small region of the brain.

　　B)The central part of the brain.

　　C)Neurons in the brain.

　　D)Oxygen-rich blood.

　　2. Which of the following statements is NOT meant by the writer?

　　A)Ceils in your brain are called neurons.

　　B)The more oxygen a neuron consumes, the more blood it needs.

　　C)FMRI helps scientists to discover which parts of the brain process information.

　　D)fMRI helps scientists to discover how the brain develops intelligently.

　　3. "Highlighting the areas of the brain at work" means

　　A)"marking the parts of the brain that are processing information"

　　B)"giving light to the parts of the brain that are processing information"

　　C)"putting the parts of the brain to work"

　　D)"stopping the parts of the brain from working"

　　4. What did the researchers experiment on?

　　A)Animals, objects, and fruits.

　　B)Two volunteers.

　　C)fMRI machines.

　　D)Thousands of pictures.

　　5. Which of the following can be the best replacement of the tide?

　　A)The Recent Development in Science and Technology.

　　B)Your Thoughts Can Be Scanned.

　　C)A Technological Dream.

　　D)A Device that can Help You Calculate.

　　答案与题解：

　　1. C 文章第二段的最后两个句子提供了答案。Cells in your brain called neurons are

　　responsible for this processin9.这里的processin9指的就是上句中的内容。

　　2. D 的电容文章中没有出现。A的内容在第二段可找到。B的内容在第二段可找到。C的内容在第五段可找到。

　　3. A highlight：使…显得突出，标出。at work：正在工作的。这里指正在处理信息的(大脑区域)。

　　4. B答案在文章的第六段中可以找到。实验者让两个自愿受试者观看许多照片，并用fMRI对设备测试他们的大脑在这一过程中的活动。

　　5.B A论述的范围太大。fMR技术已不再是梦想，所以C也不是正确选择。D所述内容与

　　文章完全不符。B符合文章内容，是最佳选择。

Putting Plants to Work

　　Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts : They've been using sunlight as an energy source for billions of years.

　　Ceils in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into1 sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you're a plant, it's difficult and expensive to convert sunlight into storable energy. That's why scientists are taking a closer look at exactly how plants do it.

　　Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Mafia Ghirardi of the National Renewable Energy Laboratory in Golden, Colo. 2, is working with green algae3. She's trying to trick them into producing hydrogen4 instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently, the hydrogen that they produce could be used to power fuel

　　Cells in cars or to generate electricity,

　　The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthesis, plants normally make sugars or starches. "But under certain conditions, a lot of algae are able to use the sunlight energy not to store starch, but to make hydrogen. " Ghirardi says. For example, algae will produce hydrogen in an air free environment. It's the oxygen in the air that prevents algae from making hydrogen most of the time.

　　Working in an air free environment, however, is difficult. It's not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate from the environment that the algae grow in, they will make hydrogen instead of sugars, even when air is present.

　　Unfortunately, removing the sulfate also makes the algae's cells work very slowly, and not much hydrogen is produced. Still, the researchers see this as a first step in their goal to produce hydrogen efficiently from algae. With more work, they may be able to speed the cells' activity and produce larger quantities of hydrogen.

　　The researchers hope that algae will one day be an easy-to-use fuel source. The organisms are cheap to get and to feed, Ghirardi says, and they can grow almost anywhere: "You can grow them in a reactor, in a pond. You can grow them in the ocean. There's a lot of flexibility in how you can use these organisms. "

　　词汇:

　　panel n. 嵌板，发热板，仪器板 miniature adj. 口巧.微型的

　　carbon dioxide 二氧化碳 algae n. 水藻，海藻

　　starch n. 淀粉 sulfate n. 硫酸盐，硫酸酯

　　photosynthesis n. 光合作用

　　注释:

　　1. convert.., into... : 将……转换为……

　　2. Colo. : Colorado，(美国科罗拉多州)的缩写形式

　　3. Green algae: 绿藻

　　4.trick them into producing hydrogen: 想方设法使它们产生氢。trick作为动词，有“欺

　　骗、哄骗”的意思，但是在这里的意思是“设法”或“采取措施”。

　　练习：

　　1. What does the writer say about plants concerning solar energy?

　　A) Plants are 'the real experts in producing solar energy.

　　B) Plants have been used to produce solar energy.

　　C) Plants have been using solar energy for billions of years.

　　D) Plants have been a source of solar energy.

　　2. Why do some scientists study how plants convert sunlight carbon dioxide, and water into sugars and starches?

　　A) Because they want algae to produce sugars and starches.

　　B) Because they want green plants to become a new source of energy.

　　C) Because they want to turn plant sugars to a new form of energy.

　　D) Because they want to make photosynthesis more efficient.

　3. According to the fifth paragraph, under what conditions are algae able to use solar energy to make hydrogen?

　　A) When there is a lot of oxygen in the air.)

　　B) When there is no oxygen in the air.

　　C) When photosynthesis is taking place.

　　D) When enough starch is stored.

　　4. Researchers have met with difficulties when trying to make algae produce hydrogen efficiently. Which one of the following is one such difficulty?

　　A) It is not possible to remove sulfate from the environment.

　　B) It is not possible to work in an airfree environment to produce hydrogen.

　　C) It is not easy to make sugars instead of hydrogen.

　　D) It is too slow for algae to produce hydrogen when the sulfate is removed.

　　5. What is NOT true of algae?

　　A) They are easy to grow.

　　B) They can be a very good fuel source.

　　C) They are cheap to eat.

　　D) They can be used in many ways.

　　6. Why do some scientists study how plants convert sunlight carbon dioxide and water into sugars and starches?

　　A) Because they want algae to produce sugars and starch.

　　B) Because they want green plants to become a new source of energy.

　　C) Because they want to turn plant sugars to a new form of energy.

　　D) Because they want to make photosynthesis more efficient.

　　答案与题解：

　　1.C 根据文章第一段最后一句的意思，c是正确选择：植物从来就利用阳光作为能源。

　　2.B文章的第三段说，科学家企图将植物或植物类生物细胞作为微型光合能源供应站来研

　　究，并举例说，他们正在用绿藻进行实验，若成功，绿藻所产生的氢将可用来为汽车的燃料电池充电。所以答案是B。

　　3.B 文章第四段告诉我们：…algae will produce hydrogen in an air free environment.没有空气的情况肯定就没有氧气了。该段最后一句又说，是氧阻止绿藻制造氢。

　　4.D选项A、B都不是正确答案，因为短文的第六段告诉我们，remove sulfate和work in

　　an air free environment都是可能的，但问题是两者都有弊端，使氢的制造不那么容易。D所述内容就是困难之一：绿藻细胞因为没有了sulfate而减缓工作速度，因此产生不了多少氢。

　　5.C 根据短文最后一段的描述，绿藻可以在任何地方生长，它们是很容易使用的燃料能源，而且用途广泛，所以，A、B、C都是正确的描述，不是答案。C是答案，因为“The organisms are cheap to get and to feed”中的feed是“养殖”的意思，不能解释为“吃”。

　　Listening to Birdsong

　　A male zebra finch1 chirps away2to himself. Suddenly he notices a female bird nearby. He realizes he has an audience and immediately changes his song. Can the female tell the difference in his performance? According to a new study, the female zebra finch knows. And she prefers the special trills he creates when he sings to her. A male zebra finch changes his song when singing to a female in ways that people can barely detect. But ~the female finch can tell the difference.

　　Scientists had noticed slight variations in the songs of mal~ zebra f'mches based on whether they were singing alone or whether there was a female (and potential mate) nearby. With an audience, the males sped up the pace of their songs and controlled the notes they used.

　　For this study, researchers Sarah C. Woolley and Allison Doupe at the University of California, San Francisco decided to focus attention on the listening females, which have not been well studied in the past.

　　In the study, Woolley and Doupe set up ,a long cage with a sound speaker at each end. One broadcast the sound of a male zebra finch singing to himself, like someone singing in the shower. The other speaker broadcast a male performing for a female audience, as if he was giving a concert.

Female birds were placed between the two speakers. Some of the birds had mates, others didn't. The females shifted around a bit, and then most of them hopped over to sit beside just one speaker. All the birds that made a clear choice liked songs meant for a female audience, even if they'd never met the male.

　　Mated females also had a chance to listen to two different performance songs, one from an unknown male, and one from their mate. They spent more time listening to the concert version of their mates' songs. This suggests that after a while, females learn to recognize--and prefer