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

    Here are some undiscovered places around the world, which will surely impress you.

Byblos, Lebanon

    This quiet settlement north of Beirut in Lebanon has been around a really long lime. Today, its rich history is well-represented in its ruins, which include ancient temples and tombs and Neolithic houses. Three sites in particular steal the show: the restored Roman amphitheatre (圆形剧场）, the grand 12^th century Crusader castle, and the beautiful]y restored medieval open market.

Carreg Cennen, Carmarthenshire, Wales

    The ruins of Carreg Cennen must be among the most noticeable sites in Wales. Carreg Cennen is defended by two drawbridges and three gate towers, although it hasn't seen much action since it was partly damaged in 1462, during the Wars of the Roses. However, one rare feature of the castle is unchanged. Ifs the stone passage that leads down to a natural cave underneath.

Providence, Rhode Island, US

    Rhode Island is the smallest state in the US. Its capital, Providence, has many of the attractions. Ivy League member Brown University and the famous Rhode Island School of Design (RISD) give the city a strong student influence. Up on College Hill, east of the Providence River, are streets lined with 18^th century wood framed houses.

Sequoia National Park, California, US

    Not content with having the worlds tallest (coast redwoods) and oldest (bristlecone pines), California is also home to the largest tree—the giant sequoia (红杉树). It grows only to its lull size in the Sierra Nevada mountains. Many of these trees are found in the Yosemite National Park, but for more quality time with the trees, it's best to head south to the far less known Sequoia National Park, which gets a quarter of Yosemite's visitor numbers.

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    Justin Bieber used to be an ordinary Canadian boy, but his life totally changed in 2008. With his great musical talent, this seventeen-year-old boy has become a superstar in the music industry.

    Justin Drew Bieber was born in 1994 in Stratford, Ontario and was raised by his single mother. Bieber learned to play musical instruments when he was very young. In 2007, he took part in a local singing competition in his hometown, and he did it just for fun. He never took singing lessons before but surprisingly he placed second in the competition. Then, with the help of his mother, he uploaded (上传) videos of him singing on a website and they successfully attracted the attention of thousands of viewers. His videos got popular through word of mouth and some of them have received up to 10,000,000 views.

    Justin Bieber would have never gotten a career in the music business without his videos. Scooter Braun, a former marketing executive (主管) of So So Def Recordings, had watched Bieber's videos and he was impressed by the boy's talent. Braun then contacted Bieber and he flew the boy into Atlanta seven months after the first video was posted. Bieber showed his talent in singing as well as his ability in playing musical instruments. He then got a record deal.

    In 2009, Justin Bieber released (发行) his first single “One Time” while he was recording the debut album (首张专辑). The single “One Time” tells a story about love. This song had success not only in Canada and the US, but also in the international market. Then he released his debut album “My World 2.0” in 2010 and the song “Baby” became the lead single. This album successfully entered the Top Ten Charts in seven countries. In June 2010, he started his first world tour in Hartford, Connecticut. One month later, he started recording his second album.

    Ever order a drink, and feel cheated on the pour? Before you trouble the waiter, take a closer look at the size of your glass. “People will generally think there being less in larger containers, than in smaller ones.” Says Theresa Marteau, a behavioral scientist at the University of Cambridge, in England.

    She and her workmates had analyzed（分析）how larger amounts—and larger plates—trick us into eating more food. And they wondered: could the same be true for alcohol?

    So the researchers convinced the employees at a local bar to run an experiment: every two weeks, for four months, they'd change the bars wine glasses from the standard 300 milliliter size, to either slightly larger—370 milliliters, or slightly smaller—250 milliliters. They saw how the size of the glass affected customers' drinking habits, even though the pour, the amount of alcoholic drinks, was unchanged.

    It turned out that serving wine in smaller glasses had no measurable effect. But the large glasses increased wine sales 10 percent-even after controlling for day of the week, temperature, holidays and so on. The reason? “When the wine, the same amount, is being served in a larger glass, people are probably thinking they've got less in there.” Which, she says, means they might drink more, believing they haven't hit their nightly limit. Or, they might just feel less satisfied with the pour, and buy another round. The study appears in the journal BMC Public Health.

    Marteau says that, if later studies confirm this effect, public health officials might consider directing a certain average glass size. “Stating clearly the largest size in which wine can be sold could be a measure to reduce the overconsumption（过度消耗）of alcohol that seems to be shown by the glass size.” Until that happens, the bar in the study now always serves its wine in the larger glasses.

    I was born in England, but I am an American. Americans like to travel on their yearly holiday. Today, more and more travelers in the United States are spending nights at small houses or inns (客栈) instead of hotels. They get a room for the night and the breakfast the next morning.

    Rooms for the night in private homes with breakfast have been popular with travelers in Europe for many years. In the past five to ten years, these bed­and­breakfast places have become popular in the United States. Many of these America's bed­and­breakfast inns are old historic buildings. Some bed­and­breakfast inns have only a few rooms; others are much larger. Some inns do not provide telephones or televisions in the rooms; others do.

    Staying at a bed­and­breakfast inn is much different from staying at a hotel. Usually the cost is much less. Staying at an inn is almost like visiting someone's home. The owners are glad to tell about the areas and the interesting places to visit. Many vacationers say they enjoy the chance to meet local families.

Learning, Fast and Deep

    Over the past five years researchers in artificial intelligence have become the rock stars of the technology world. A branch of AI known as deep learning, which uses neural(神经的) networks to scan through large volumes of data looking for patterns, has proven so useful that skilled practitioners can command high six-figure salaries to build software for Amazon, Apple, Facebook and Google.

    The standard route into these jobs has been a PhD in computer science from one of America's top universities. Earning one takes years and requires a personality suited to academia, which is rare among more normal folk.

    That is changing.

    Last month fast.ai, a non-profit education organization based in San Francisco, kicked off the third year of its course in deep learning. Since its foundation it has attracted more than 100, 000 students around the globe from India to Nigeria. The course and others like it, come with a simple idea: there is no need to spend years obtaining a PhD in order to practise deep learning. Creating software that learns can be taught as a craft, not as a high intellectual pursuit to be undertaken only in an ivory tower. Fast. ai's course can be completed in just seven weeks.

    To make it accessible to anyone who wants to learn how to build AI software is the aim of Jeremy Howard, who founded fast.ai with Rachel Thomas, a mathematician. He says school mathematics is sufficient. "No. Greek. Letters," Mr. Howard intones, pounding the table with his fist for punctuation.

    Some experts worry that this will serve only to create a flood of unreliable AI systems which will be useless at best and dangerous at worst. In the earliest days of the Internet, only a select few nerds, namely computer holies with specific skills, could build applications. Not many people used them. Then the invention of the World Wide Web led to an explosion of web pages, both good and bad. But it was only by opening up to all that the Internet gave birth to online shopping, instant global communications and search. If Mr. Howard and others have their way, making the development of AI software easier will bring forth a new crop of fruit of a different kind.