Sleep is something we all do. But some people need to sleep more than others. Babies sleep most of the time. Children in school sleep about ten to twelve hours a night. Most adults sleep only seven or eight hours.{#blank#}1{#/blank#}All parts of our bodies have to rest after they work.. Our arms need a rest after we lift heavy thing, When we run fast, our legs work hard. They get tired. We have to rest them. Our brains workhard, too.{#blank#}2{#/blank#} We can sit quite still and rest our arms andlegs. But our brains aren't resting. They go right on thinking as long as weare awake.

      Our brains slow down a bit when we sleep and dream.{#blank#}3{#/blank#} Instead of thinking wide-awake thoughts, our brains make up dreams. Some dreams are very pleasing. Some are not. Most of thetime we forget them when we wake up.

      Scientists have tried to find out what would happen if people were not allowed to sleep. They asked some people not to go to bed. The people stayed up all night and all the next day. They stayed up the next night too,and the day after. They played games, but they made mistakes. They forgot things.{#blank#}4{#/blank#} The people grew rude and mean. They became angry with their friends. Finally they were too tired to stand up. When they sat down, they fell asleep.

Scientists have found that if people are not allowed to sleep and to dream, they act in an unusual way.{#blank#}5{#/blank#}But we do know that we need it to stay well. So tonight have a goodsleep. Lie down under the covers. Shut your eyes. Let your thoughts wander.Soon you'll stop thinking. You'll be asleep.

A. It was hard for their tired brains to work.

B. When we are awake, they help us pay attention to the worldaround us

C. But babies, children, and adults—all of us need to haveour sleep

D. Good sleep helps to improve one's memory

E. No one knows why sleep is so good for us

F. But even as we sleep our brains are doing some work

G. Of course you will have a good sleep

    Life in the Clear

    Transparent animals let light pass through their bodies the same way light passes through a window. These animals typically live between the surface of the ocean and a depth of about 3,300 feet—as far as most light can reach. Most of them are extremely delicate and can be damaged by a simple touch. Sonke Johnsen, a scientist in biology, says, “These animals live through their life alone. They never touch anything unless they're eating it, or unless something is eating them.”

    And they are as clear as glass. How does an animal become see-through? It's trickier than you might think.

    The objects around you are visible because they interact with light. Light typically travels in a straight line. But some materials slow and scatter(散射) light, bouncing it away from its original path. Others absorb light, stopping it dead in its tracks. Both scattering and absorption make an object look different from other objects around it, so you can see it easily.

But a transparent object doesn't absorb or scatter light, at least not very much, Light can pass through it without bending or stopping. That means a transparent object doesn't look very different from the surrounding air or water. You don't see it —-you see the things behind it.

    To become transparent, an animal needs to keep its body from absorbing or scattering light. Living materials can stop light because they contain pigments(色素) that absorb specific colors of light. But a transparent animal doesn't have pigments, so its tissues won't absorb light. According to Johnsen, avoiding absorption is actually easy. The real challenge is preventing light from scattering.

Animals are built of many different materials—-skin, fat, and more—-and light moves through each at a different speed. Every time light moves into a material with a new speed, it bends and scatters. Transparent animals use different tricks to fight scattering. Some animals are simply very small or extremely flat. Without much tissue to scatter light, it is easier to be see—through. Others build a large, clear mass of non-living jelly-lie(果冻状的)material and spread themselves over it .

    Larger transparent animals have the biggest challenge, because they have to make all the different tissues in their bodies slow down light exactly as much as water does. They need to look uniform. But how they're doing it is still unknown. One thing is clear for these larger animals, staying transparent is an active process. When they die, they turn a non-transparent milky white.

    Hold your smartphone, smile at the front camera, and click! You get a selfie. There is no doubt that this photo is yours. But if a monkey takes a selfie, does the camera owner have the right to decide how to use it?

    Recently, this question has caused a problem between Wikimedia Foundation, a non-profit organization, and British wildlife photographer David J. Slater.

    In 2011, Slater was visiting a park in Indonesia when a macaque(猕猴) got hold of one of his cameras. “They were quite naughty, jumping all over my equipment,” Slater told The Telegraph, “and it looked like they were already posing for the  camera when one hit the button.” The result was hundreds of monkey selfies. The best of images was a female macaque grinning toothily into the lens.

    This week, the grinning monkey selfie returned to the news when Wikimedia refused Slater's request to take the photos down from Wikimedia Commons, a website that is run by the organization and offers free images.   5

According to Wikimedia, anyone who downloads the monkey selfie, or any of the millions of images on the site, can “copy and use any works here freely as long as they follow what the author says.” The question that arose here was whether Slater, who had not held the camera, set up the shot, or pressed the shutter(快门) button, could be considered the photographer of the monkey selfie. Wikimedia's position on this was clear: as the work of a non-human animal, this photo has no human author who owns the copyright.”

    Only authors of creative works, like a piece of writing or a song, own copyrights. In terms of photos, US copyright law says whoever pushes the button on the camera owns the copyright to the image produced, which means that if tourists ask you to take a photo of them, and you happen to hit the shutter button at the exact moment that Justin Bieber, a Canadian singer, made faces behind them. You, as the photographer, would have the photo's copyright and sell it. The tourists, who own the camera on which the photo was taken and asked you to take the photo don't get the right to use it without you allowing them to. All this has been complicated by the appearance of surveillance cameras(监控摄像头), smart phones, and large-scale photography projects for which assistants often press the shutter button to produce works whose copyrights belong to their boss.

    Slater seems to be thinking along these lines. He says that buying the cameras, spending thousands of pounds to transport himself to Indonesia, and allowing the monkeys to “steal” his cameras makes him the author of the image, regardless of who pushed the button. “In law, if I have an assistant then I still own the copyright,” he told the “Today” Show. “I believe in this case, the monkey was my assistant.”

    If that seems unfair, think about this. If a person left her laptop in a café, and a poet picked it up, opened up a word-processing program, and typed out a poem which turned out to be the best poem of this generation, could she ask for much more than her laptop back?

    This may be music to your ears. Researchers P. Jason Rentfrow and Samuel Gosling gave 3,500 people a personality（人格、个性）quiz. "We found that the musical styles people like are closely linked to their personalities," Gosling says.

    RAP/HIP-HOP

    Known for their quick speech, some rappers can say more than 700 syllables（音节）a minute! If you like rap/hip-hop, you are energetic and have a way with words. You put a fresh spin on things, whether it's new moves on the dance floor or your hip style.

    CLASSICAL

    In the 18th century, classical musicians were like rock stars. Beethoven and Mozart, for example, played in crowded concert halls. If you like classical, you are open to new ideas and like debating with friends. Creative and imaginative, you can easily spend many hours scrapbooking（剪贴）, writing or painting.

    COUNTRY

    Country music came from the folk songs of English, Scottish, and Irish settlers of the southeastern United States. If you like country, you express your opinions well, which makes you the ideal class president or team captain. Traditional and loyal, you enjoy spending time with your family.

    POP

    Pop music is designed to attract almost everyone, and it does. Each year, the industry brings in about 30 billion dollars! If you like pop, you are attractive to your friends. You can make big things happen, like planning for a huge party or inspiring your team to victory.

    ROCK/ALTERNATIVE

    In the 1950s, rock music created a brand-new culture. Teenagers, for the first time, had an identity separate from adults and children. If you like rock/alternative, you are a risk-taker who never accepts no for an answer. You rise to any challenge, like doing very well in a big exam or landing the lead in the school play.

    If these personality profiles（人格剖析）don't match you, that's OK. These are just for fun.

    By now you've probably heard about the "you're not special" speech, when English teacher David McCullough told graduating seniors at Wellesley High School: "Do not get the idea you're anything special, because you're not." Mothers and fathers present at the ceremony 一 and a whole lot of other parents across the Internet — took issue with McCullough's ego-puncturing (伤自尊的) words. But lost in the uproar (喧嚣)was something we really should be taking to heart: our young people actually have no idea whether they're particularly talented or accomplished or not. In our eagerness to elevate their self-esteem, we forgot to teach them how to realistically assess their own abilities, a crucial requirement for getting better at anything from math to music to sports. In fact, it's not just privileged high-school students: we all tend to view ourselves as above average.

    Such inflated self-judgments have been found in study after study and it's often exactly when we're least competent at a given task that we rate our performance most generously, in a 2006 study published in the journal Medical Education, for example, medical students who scored the lowest on an essay test were the most charitable in their self evaluations, while high-scoring students judged themselves much more strictly. Poor students, the authors note, "lack insight" into their own inadequacy. Why should this be? Another study, led by Cornell University psychologist David Dunning, offers an enlightening explanation. People who are incompetent, he writes with coauthor Justin Kruger, suffer from a “dual burden": they're not good at what they do, and their very clumsiness prevents them from recognizing how bad they are.

    In Dunning and Kruger's study, subjects scoring at the bottom on tests of logic, grammar and humor -extremely overestimated'' their talents. Although their test scores put them in the 12th percentile (百分位数) they guessed they were in the 62nd. What these individuals lacked (in addition 9 clear logic, proper grammar and a sense of humor) was "meta cognitive skill" the capacity to monitor how well they're performing. In the absence of that capacity, the subjects arrived at an overly hopeful view of their own abilities. There's a paradox here, the authors note: The skills that lead to competence in a particular domain are often the very same skills necessary to evaluate competence in that field? In other words, to get better at judging how well we're doing at an activity, we have to get better at the activity itself.

    There are a couple of ways out of this double bind. First, we can learn to make honest comparisons with others. Train yourself to recognize excellence, even when you yourself don't possess it, and compare what you can do against what truly excellent individuals are able to accomplish. Second, seek out feedback that is frequent, accurate and specific. Find a critic who will tell you not only how poorly you're doing, but just what it is that you're doing wrong. As Dunning and Kruger note, success indicates to us that everything went right, but failure is more ambiguous: any number of things could have gone wrong. Use this external feedback to figure out exactly where and when you screwed up.

    If we adopt these strategies — and most importantly, teach them to our children — they won't need parents, or a commencement (毕业典礼)speaker, to tell them that they're special. They'll already know that they are, or have a plan to get that way.

    In the first few years of their lives, children brought up in English-speaking homes successfully master the use of hundreds of words, including those for objects, actions, emotions, and many other aspects of the physical world. However, when it comes to learning colour words, the same children perform very badly. If shown a blue cup and asked about its colour, typical two-year-olds seem as likely to come up with "red" as "blue".

    Cognitive (认知) scientists at Stanford University in California supposed that children's incompetence at colour-word learning may be directly linked to the way these words are used in English. They are used mostly in pre-nominal position (e.g. "blue cup"), in contrast to post-nominal position (e.g. "The cup is blue."). The difficulty children have may simply come down to the challenge of having to make predictions from colour words to the objects they refer to, rather than from the objects to the colour words.

    To explore this idea further, the research team recruited 40 English children aged between 23 and 29 months and carried out a three-phase experiment. It considered of a pre-test, followed by training in the use of colour words, and finally a post-test that was identical to the pre-test. The pre- and post- test materials comprised six objects that were unfamiliar to the children. There were three examples of each object in each of three colours — red, yellow and blue. The objects were presented on trays (托盘), and in both tests, the children were asked to pick out objects in response to requests in which the colour word was either a pre-nominal ("Which is the red one?") or a post-nominal ("Which one is red?").

    In the training, the children were introduced to five sets of familiar items (balls, cups, crayons, glasses, and toy bears) in each of the three colours. Half the children were presented with the items one by one and heard them labeled with colour words used pre-nominally, while the other half were introduced to the same items described with a post-nominal colour word. After the training, the children repeated the selection task on the novel items in the post-test. Correct choices on items that were consistent across the pre- and post-tests were used to measure children's colour knowledge.

    According to the assessment, children's performance was consistent when they were both trained and tested on post-nominal adjectives, and worst when trained on pre-nominal adjectives and tested on post-nominal adjectives. Comparing the pre- and post-test scores across each condition revealed a significant decline in performance when children were both pre- and post-tested with questions that placed the colour words pre-nominally.