Polar bears are one of the most popular animals for people. Polar bears are different from every other bear in the world. This is because polar bears have white fur. However, there are many facts about polar bears that people might not be aware of .

    The skin of polar bears is black, which according to thinkquest.org allows them to absorb more heat from the sun. Polar bear fur is transparent , because it is made up of hollow guard hairs. Loc.gov explains that the reason polar bears display white fur is that when the sun hits the fur ,the hollow spaces in the hair scatter the light. Since none of the light is absorbed, the light reflected back appears white to human eyes.

    Polar bears' conservation status is considered close to extinction. Global warming is considered the main cause of the decline in polar population. Polar bears use ice floats to hunt for their food. However, these ice floats are melting so polar bears are starting to drown in the search for food, and the food is becoming more difficult to get. Contrary to popular belief, polar bears do not eat penguins, because polar bears are not found in the Antarctic region of the world. Polar bears are only found around the Arctic Circle. Polar bears do not drink water. They get all the water they need from the prey they eat.

    FES. Gov specifies that polar bears are considered the largest land carnivores(食肉动物) in the world. The polar bear weight ranges between 700--1,500 pounds. Since the polar bear habitat is melting away, their main evolutionary advantages are fading. Polar bears are not able to use their camouflage(伪装) to find prey in habitats not covered with snow. Polar bears do not hibernate(冬眠). However, when the weather gets uncomfortable, or mothers give birth, polar bears will dig themselves a hidden home.

    What can we do to help save the polar bears? We can donate to organizations like the World Wildlife Fund, reduce our carbon footprint, and send letters to politicians explaining to them that we need to set up more preserves to help save the polar bear habitat.

How Room Designs Affect Our Work and Feelings

    Architects have long had the feeling that the places we live in can affect our thoughts, feelings and behaviors. But now scientists are giving this feeling an empirical（经验的，实证的） basis. They are discovering how to design spaces that promote creativity, keep people focused and lead to relaxation.

    Researches show that aspects of the physical environment can influence creativity. In 2007, Joan Meyers-Levy at the University of Minnesota, reported that the height of a room's ceiling affects how people think. Her research indicates that higher ceilings encourage people to think more freely, which may lead them to make more abstract connections. Low ceilings, on the other hand, may inspire a more detailed outlook.

    In additions to ceiling height, the view afforded by a building may influence an occupant's ability to concentrate. Nancy Wells and her colleagues at Cornell University found in their study that kids who experienced the greatest increase in greenness as a result of a family move made the most gains on a standard test of attention.

    Using nature to improve focus of attention ought to pay off  academically, and it seems to, according to a study led by C. Kenneth Tanner, head of the School Design & Planning Laboratory at the University of Georgia. Tanner and his team found that students in classrooms with unblocked views of at least 50 feet outside the window had higher scores on tests of vocabulary, language arts and maths than did students whose classrooms primarily overlooked roads and parking lots.

    Recent study on room lighting design suggests than dim（暗淡的） light helps people to loosen up. If that is true generally, keeping the light low during dinner or at parties could increase relaxation. Researchers of Harvard Medical School also discovered that furniture with rounded edges could help visitors relax.

    So far scientists have focused mainly on public buildings. "We have a very limited number of studies, so we're almost looking at the problem through a straw（吸管）," architect David Allison says. "How do you take answers to very specific questions and make broad, generalized use of them? That's what we're all struggling with."

    When Iwas.in the third grade, we had a hunt at school. We gathered up chalk，pencils，stones, and so on, rapidly filling our checklists. It was a very close race. I was out of breath when I reached the clover (三叶草)patch in search of the last, most hard-to-find item: a four-leaf clover.

    I was pretty sure that I was going to win. 1 have always been able to find four-leaf clovers. I just see them.

    I spent my childhood collecting and pressing four-leaf clovers into books at my mother's house. I started with big cloth- and leather-bound books. When I ran out of romantically bound volumes, I began to put my treasures into anything I could find: fiction paperbacks, cookbooks. The same is true in my house today. Shake a book, and a papery treasure just might fall into your hand.

    A few years ago, in Nova Scotia, my husband and I pulled off the road for a picnic. The ground was thick with clover. Some shoots had four, five, even six leaves. I lined them up on the picnic table to admire as my husband, never yet having found one four-leaf clover, looked on with awe. To me, it was simple. The differences in their shapes popped out, breaking the pretty pattern of the conventional clovers with their three perfect leaves.

    Two summers back, while waiting for an airport shuttle in Munich, I found a tiny four-leaf clover in a traffic circle and put it into my passport. On the way home, my husband and I were upgraded to business class. Friends attributed our good luck to the clover. I think, it's more likely that we were upgraded because a kind customer service officer took pity on us.

    People disagree about whether the luck lies in the finding or in the possession of a clover. Some believe that the luck is lost if the four-leaf clover is even shown to somebody else, while others think the luck doubles if it is given away. I believe that positivity is increased by sharing. I feel lucky to find the clovers so often, but I don't think they influence my life any more than it does to share anything a little special—that momentary closeness between you and a friend or a stranger, as you all lean in to wonder at a rare find.

    Any foreigner who has tried to learn Chinese can tell how hard it is to master the tones required to speak and understand. And anyone who has tried to learn to play the violin or other instruments can report similar challenges.

    Now researchers have found that people with musical training have an easier time learning Chinese. Writing in the online edition of Nature Neuroscience，researchers from Northwestern University say that both skills draw on the same parts of the brain that help people discover changes in pitch(音调).

    One of the study's authors，Nina Kraus，said the findings suggested that studying music "actually tunes our sensory system" .This means that schools that want children to do well in languages should hesitate before cutting music programs，Dr. Kraus said. She said music training might also help children with language problems.

    Mandarin(普通话)speakers have been shown to have a more complex encoding(编码) of pitch patterns in their brains than English speakers do. This is because in Mandarin and other Asian languages，pitch plays a central role. A single­syllable word can have several meanings depending on how it is intoned.

    For this study，the researchers looked at 20 non­Chinese speaking volunteers，half with no musical background and half who have studied an instrument for at least six years.

    As they were shown a movie，the volunteers also heard an audio tape of the Mandarin word “mi” in three of its meanings: squint，bewilder and rice. The researchers recorded activities in their brain stems to see how well they were processing the sounds. Those with a music background showed much more brain activities in response to the Chinese sounds.

    The lead author of the study，Patrick C.M. Wong，said it might work both ways. It appears that native speakers of tonal languages may do better at learning instruments.

    Buster used to be a lovely dog playing and running on a farm all day. His life had a big change after his handler Will's presence because Will found he did extremely well in sniffing tests. Will thought Buster had a special talent and decided to let him become a member of RAF police working dogs. Buster began working with Will in 2007, and the pair was sent to Afghanistan's deadly Helmand province. There, Buster saved countless lives by sniffing out explosive devices (IEDs), as well as weapons. He joined his comrades repeatedly on foot patrols hunting Taliban terrorists and tracking down bombs. He also acted as a useful diplomatic tool, due to his friendly approach to local children. The RAF soon had a long train of children in tow, as Buster drew in his crowd and entertained them.

    After his glittering service with the RAF, Buster retired in 2011,and died in 2015 at the age of 13 at the home of his handler, Will, in Lincolnshire where he had been enjoying retirement with his handler Will, his wife Tracy and their two dogs who will inherit (继承) their father's career.

    Over the course of his career, Buster is thought to have saved more than 1,000 lives. He also helped patrol British bases and searched vehicles at check points, and upon retirement was made the official RAF Police mascot (吉祥物). Buster's brave exploits were even documented in Will's book, which was published in January and soon became a best-selling one.

    Buster completed five tours of duty in Afghanistan, Bosnia and Iraq and earned a row of campaign medals, and it was because of his great efforts in these austere environments full of wars and confrontations that he would be remembered. It was the saving of countless lives by searching out IEDs that saw the honor of official lifetime mascot of the RAF Police bestowed (授予) upon Buster. The RAF police are now planning to commemorate Buster as part of a special event to celebrate RAF Police Working Dogs.