An absolute description of the threat hanging over the world's mammals,reptiles,amphibians and other life forms has been published by the well-known scientific journal,Nature.A special analysis carried out by the journal indicates that an astonishing 41% of all amphibians on the planet now face extinction while 26% of mammal species and 13% of birds are similarly threatened.

    Many species are already critically endangered and close to extinction,including the Sumatran elephant,Amur leopard and mountain gorilla.But also in danger of vanishing（消失）for the wild,it now appears,are animals that are currently rated as merely being endangered.

    In each case,the finger of blame points directly at human activities.The continuing spread of agriculture is destroying millions of hectares of wild habitats every year,leaving animals without homes,while the introduction of newly-come species,often helped by humans,is also damaging native populations.At the same time,pollution and overfishing are destroying ocean ecosystems.

    "Habitat destruction,pollution or overfishing either kill off wild creatures and plants or leaves them badly weakened," said Derek Tittensor,an ocean ecologist at the World Conservation Monitoring Centre in Cambridge. "The trouble is that in coming decades,the additional threat of worsening climate change will become more and more common and could then kill off these survivors."

    The problem,according to Nature,is worsened because of the huge gaps in scientists knowledge about the planet's biodiversity.Evaluations of the total number of species of animals and plants alive vary from 2 million to 50 million.In addition,evaluations of current rates of species' disappearances vary from 500 to 36,000 a year. "That is the real problem we face," added Tittensor. "The scale of uncertainty is huge."

    In the end,however,the data indicate that the world is heading cruelly towards a mass extinction-which is defined as one involving a loss of 75% of species or more.This could arrive in less than a hundred years or could take a thousand,depending on extinction rates.

    The old man walked with a cane (拐杖) slowly into the restaurant. His poor jacket, patched (打补丁的) trousers, and worn-out shoes made him stand out from the usual Saturday morning breakfast crowd. Unforgettable were his pale blue eyes that sparkled (闪光) like diamonds, large rosy cheeks, and thin lips that held a steady smile. He walked toward a table by the window. A young waitress watched him and ran over to him, saying, “Here, Sir. Let me give you a hand with that chair.” Without a word, he smiled and nodded a thank you. She pulled the chair away from the table. Supporting him with one arm, she helped him move in front of the chair, and get comfortably seated. Then she pushed the table up close to him, and leaned his cane against the table where he could reach it. In a soft, clear voice he said, “Thank you, Miss.” “You're welcome, Sir.” She replied. “My name is Mary. I'll be back in a moment. If you need anything, just wave at me.”

    After he had finished a hearty meal of pancakes, bacon, and hot lemon tea, Mary brought him the change, helping him up from his chair and out from behind the table. She handed him his cane, and walked with him to the front door. Holding the door open for him, she said, “Come back and see us, Sir!” He nodded a thank you and said softly with a smile, “You are very kind!”

    When Mary went to clean his table, she was shocked. Under his plate she found a business card and a note written on the napkin, under which was a $ 100 bill. The note on the napkin read, “Dear Mary, I respect you very much, and you respect yourself, too. It shows by the way you treat others. You have found the secret of happiness. Your kind gestures will shine through those who meet you.”

    The man she had served was the owner of the restaurant. This was the first time that she, or any of his employees, had seen him in person.

    National Rankings: Best High Schools

    The U.S. News rankings include data on more than 22,000 public high schools in 50 states and the District of Columbia. Schools were awarded gold, silver or bronze medals based on their performance on state assessments and how well they prepare students for college.

    About the Awards

    Gold—Top 500 Schools based on highest college readiness.

    Silver—High-performing schools based on lower college readiness.

    Bronze—High-performing schools based on state exam performance,  listed alphabetically.

    Award Distribution

    Gold 2.4%

    Silver 10.3%

    Bronze 16.8%

    No Medal 70.5%

    HOW We Determine the Awards

    STEP 1 Students perform better than expected in their state.

    We looked at reading and math results for students on each state's proficiency(水平) tests and then factored in the percentage of economically disadvantaged students, who tend to score lower.

    STEP 2 Disadvantaged students perform better than state average.

    We compared each school's math and reading proficiency rates for disadvantaged students--black, Hispanic and low-income—with the state wide results for these student groups and then selected schools that were performing better than their state averages.

    STEP 3 Student graduation rates meet or are greater than a national standard.

    We left out schools from consideration if their graduation rates were lower than 75 percent--a starting point that is higher than a federal law that requires states to give extra resources to schools below 67 percent.

    STEP 4 Students are prepared for college-level coursework.

    We calculated a College Readiness Index,which is based or the school's AP participation rate and how well the students did on those tests. Tiebeakers were used to determine ranks of schools that achieved the same College Readiness Index.

    “That one looks just like a sheep! And look over there. That one looks like a horse!” Do you remember lying on your back in a grassy field on a summer afternoon, discovering the soft shapes in the clouds in the sky? Those were the good old days when you could see anything and everything in the clouds.

    But now people look at the sky and see clouds in the shape of a motor company's advertising logo (商标),or a message inviting them to go out and buy a certain brand (品牌) of beer. These cloud pictures are not products of their imaginations. Instead, they are produced by a machine. These new floating advertisements are called Flogos; the name stands for “floating logos.” They' re made from a mixture of soapy foam (泡沫)and a lighter-than-air gas such as helium, and they can be made into different sizes and shapes depending on the advertisement.

    Flogos can last up to an hour if weather conditions are good, and they can fly several kilometers high. Advertisers can rent a Flogo machine for$2,500 a day. The set-up is normally performed within 1 to 2 hours, and it will release four Flogos per minute. Advertisers can fill the air with any shape or message they want.

    Some people are worried that the Flogos might not be pollution-free. However, the Flogo's inventor insists that the soap he uses is natural, and that a Flogo just dissipates in the air, leaving nothing behind. Though it may be true that Flogos are environmentally friendly, some people believe that the natural clouds in our memory may be replaced by man-made ones. They are afraid that soon there will be nowhere left where their imaginations can float freely.

    Have you ever complained, "I remember reading it, but I can't remember what it said? " then you should try the SQ4R reading method.

    S = Survey. The first step is to take a few minutes skimming the chapter. Don't read it yet, just look at topic headings, key words, and read the summary.

    Q = Question. As you prepare to read the chapter, turn the first topic into a question or two. As you read, seach for the answer. This will help you organize your reading-find the parts that answer your question, give an example, consist of related information or that may answer a later question. Most importantly, this gives you a reason to read the next paragraph.

    R = Read. Read in short "bites" (部分), then determine how that answers question(s) you originally posed (提出). Often as you read other questions will arise.

    R = Recite. Now can you answer your question(s) in your own words? If you can't, reread the material to find the answers or determine if you need to change the question. You are rehearsing (重复，默诵) for the time when you will need o know the answer. A good technique for rehearsing answers is to briefly jot down (草草记下) the key words that remind you of the essence of the answer without writing down every detail.

    R = Relate. Most of us try to relate what we are reading to what we already know. It is always easier and more satisfying to remember information that is personally meaningful. Everything has a context. Some information may take more reflection before you are able to grasp its relationship with what you already know while other information may simply require more research, to understand how it fits with other data.

    R = Review. One way to minimize memory decay (衰退) and to store the material you have studied firmly in your mind is by reviewing it. After you finish reading the entire chapter, skim back over it and any note you made.

    Effective studying requires effective reading. Rather than getting "intellectual indigestion" while reading straight through a chapter, instead you should stop to survey, question, read, recite, relate, and review so as to improve your reading comprehension.

    He is regarded as having one of the brightest minds on the planet. But outstanding astrophysicist (天体物理学家) Stephen Hawking has admitted that he did not learn to read until he was eight years old.

    In a public lecture at the Royal Albert Hall, Professor Hawking also admitted that he was not active in studying while at Oxford University, where he studied physics, and that only the diagnosis that he might die young from motor neurone (神经元) disease made him concentrate on his work.

    Professor Hawking said: "My sister Philippa could read by the age of 4 but then she was definitely brighter than me." He said that he was unexceptional at school and was never further than halfway up his class. "My classwork was very untidy, and my handwriting was the despair of my teachers," he said. "But my classmates gave me the nickname Einstein, so presumably they saw signs of something better."

    But he said that it was when doctors told him that he probably only had a few years to live at the age of 21 that galvanized him into focusing on his work and a period of productivity that resulted in some of his early breakthroughs. He said, "When you are faced with the possibility of an early death, it makes you realize that life is worth living and there are lots of things you want to do."