When the Normans built their first simple wooden castles in England，they built them on the top of small hills.The first permanent castles were made of stone and built with thick walls.The main building was usually surrounded by walls which overlooked the moat (护城河)．

     The entrance to the castle was usually over a drawbridge (吊桥) leading to the main gatehouse.The drawbridge could be raised or lowered and an iron grille (栅栏) could be lowered to shut off the entrance to the gatehouse.

     As time went on，the castle builders became more advanced in their techniques.Instead of building a strong central building and surrounding it with walls of lesser strength，they thought out the idea of surrounding a central area with huge walls which could contain all the main rooms of the castle.These walls usually had many towers and these towers were really a series of main buildings along the castle walls.In building these castles they used hill sites whenever possible in order to give the castle a better position.Because the outside world was shut off by a barrier or curtain of defences，they are called “curtain wall” castles.

     With the passing of time there was less need to build strong castles and nobles built manor (庄园) houses.These manor houses often had battlements and iron grilles，but they were built more for comfort and included many of the conveniences and luxuries of the large houses which were being built in the towns.

     Unfortunately，many English castles were damaged or destroyed completely during the Civil Wars of the 1600s.

    I am a volunteer. I set out to help clean up the beach after a violent storm a year ago. The sight I saw was heartbreaking. The broken houses seemed to be crying. I couldn't describe how I felt. But something special among the debris (废墟) turned my day around.

    I joined a club to clean up the beach after the storm last November. As I removed the debris from the beach, I noticed an object with shiny buttons in the wet sand. It was a jacket，and I was excited since Halloween(万圣节) was coming and I thought I had found a great costume(戏服). After picking it up, I was able to see that the jacket was from West Point (西点军校), the United States Military Academy, and it had the name “deGavre” written inside. I realized the jacket might be important to someone. I decided to find the jacket's owner and return it.

    I called the West Point Museum, considering that if the family couldn't be found, the jacket should go there. The museum connected me with Kim McDermott, Director of Communications for the Academy's Association of Graduates. Kim soon ensured that the jacket had belonged to Chester Braddock deGavre, who was a 1933 graduate and a war hero, but passed away in 1993.

    I sent Kim a photo of the jacket and she posted it to the West Point Association of Graduates Facebook Page, asking if anyone could help us find the family. In less than two hours, someone had found and called the hero's wife, Teresa. Soon I started to receive personal messages from members of the deGavre family, their friends and others who were touched by the story and they found me on Facebook.

    Finding Chester deGavre's jacket and connecting to his family with the help of Facebook have been so meaningful to me. I've formed a bond(纽带) with amazing people I might have never met.

    In 1869, the Smiley family purchased an area of land about 100 miles north of New York City. Over time, some of their property and much of the surrounding landscape became the Mohonk Preserve, which has since grown to 8,000 acres and attracts visitors and rock climbers.

    But the Mohonk Preserve also has a long scientific legacy. In the 1930s, Dan Smiley, a descendent of the original owners, began keeping track of the plants and animals that lived in the area.

    Megan Napoli is a research ecologist with the Mohonk Preserve in New York. She thinks Smiley's efforts produced a rare long-term data set of observations, which is useful for studying the impacts of climate change. For instance, other research has shown that songbirds are migrating north earlier and earlier in the spring.

    It's important for the birds to arrive at the proper time in the spring, because they need to time their arrival with the insect emergence. So they need to be here to establish their nesting sites, lay their eggs. Once the eggs hatch, they have their baby birds, so they need to time it when the insects are most abundant.

    Napoli has begun analyzing about 76,000 observations of songbird migration dates collected by Smiley and his team to see if they, too, show that climate change has altered the timing of migrations. Her results suggest that they do.

    Napoli found that short-distance migrants that spend their winters in the southern U. S. now arrive an average of eleven days earlier than they did in the 1930s. Long-distance migrants that overwinter in the tropics arrive roughly a week earlier. Napoli presented her results at a recent Ecological Society of America meeting in Portland, Oregon.

    Meanwhile, who knows how many other long-term, personal data collections like Smiley's are out there, waiting to be discovered and to help improve official attempts to track the planet's changes.

    During this shopping season, salesmen will come up with different strategies to get your business. Many product companies use specific colors to cause positive emotions and compete for a sale. However, sight is not the only sensory (感官的) retail that companies use. Sounds and smells can also influence consumers' purchasing decisions.

    Nobel Prize-winning research shows that our sense of smell has great power to cause an emotional response. A study published earlier this year compared purchasing in a French flower shop when the smell of lavender (薰衣草) was given off and when it wasn't. It found that the smell increased the number of consumers' purchasing items and the amount of their purchases. An earlier study using Nike shoes found that consumers desired the shoes more, and were willing to pay more, when the room had a mixed smell of flowers. Realizing the subconscious impact of smell, many stores apply artificial scents (气味) through their heating and air-conditioning vents (通风口) or place scent machines above their doors. For instance, a coconut scent might make that bikini more appealing as you long for a vacation.

    Ever felt frenzied due to a store's fast-paced music? Or calmed by a piece of light music? A retailer's choice of music can have a big impact on consumers' moods. One study found that when subjected to loud music, consumers will spend less time in a store. But interestingly, the researchers did not find a difference in sales or customers' satisfaction. Another interesting finding from a recent study was that customers actually shop longer when exposed to unfamiliar music. Just as department stores use different scents in certain departments, many use different music in some areas to appeal to varying consumers.

    Well, you could always leave the store and take a break, but the food court probably isn't your best choices as brands like Cinnabon and Panera Bread also use scents as part of their customers' experience. Online retailers (零售商) use a variety of other strategies to get your business, but you can always neglect those and enjoy the familiar scents of home.

    Barbara McCintock was one of the most import scientists of the twentieth century. She made important discoveries about genes（基因） and chromosomes （染色体）.

    Barbara McClintock was born in 1902 in Hartford, Connecticut. Her family moved to Brooklyn area of new York City in 1908. Barbara was an active child with interests in sports and music. She also developed an interest in science.

    She studied science at Cornell University in Ithaca, New York. Barbara was among a small number of undergraduate students to receive training in genetics in 1921. Years later, she noted that few college students wanted to study genetics.

    Barbara McClintock decided to study botany, the scientific study of plants, at Cornell University. She completed her undergraduate studies in 1923. McClintock decided to continue her education at Cornell. She completed a master's degree in 1925. Two years later, she finished all her requirements for a doctorate degree.

    McCintock stayed at Cornell after she completed her education. She taught students botany. The 1930s were not a good time to be a young scientist in the United States. The country was in the middle of the great economic Depression. Millions of Americans were unemployed. Male scientists were offered jobs. But female geneticists were not much in demand.

    An old friend from Cornell, Marcus Rhoades, invited McClintock to spend the summer of 1941working at the Cold Spring Harbor Laboratory. It is a research center on Long Island, near New York City. McClintock started in a temporary（临时的）job with the genetics department. A short time later, she accepted a permanent （永久的） position with the laboratory. This gave her the freedom to continue her research without having to teach or repeatedly ask for financial aid.

    By the 1970s, her discoveries had an effect on everything from genetic engineering to cancer research. McClintock won the Nobel Prize for Physiology or Medicine in 1983for her discovery of the ability of genes to change positions on chromosomes. She was the first American woman to win an unshared Nobel Prize.

Below is a list of women who changed the world when they were young girls and teens.

Mary Shelley

English author Mary Shelley was just 18 years old when she wrote Frankenstein, which many credit as the origin of science fiction. Thus, Shelley has been called "the teenage girl who invented science fiction."

Alexandra Scott

Alexandra Scott was diagnosed with a form of cancer shortly before her first birthday. When she was just 4 years old, she set up her first lemonade stand in her front yard to raise money for childhood cancer research. Inspired by her story, people around the world set up their own lemonade stands to raise money for her cause. By the time she died in 2004, she had raised SI million. Her family continues her legacy (遗志) through Alex's Lemonade Stand Foundation.

Yuanyuan Tan

Chinese ballet dancer Yuanyuan Tan started representing her country in international competitions as a young teen. At 17, she became the youngest ever principal dancer at the San Francisco Ballet, as well as the first Chinese dancer to earn that title in a major Western company. She gives talks around the world, inspiring young dancers to follow their artistic dreams.

Bindi Irwin

Bindi Irwin carried on her father Steve Irwin's conservation legacy following his death in 2006. When she was 8 years old, she launched "Bindi the Jungle Girl" to encourage more kids to get interested in animals and wildlife conservation. She has continued to make TV appearances, published books and furthered her father's causes.