全新大学英语视听阅读Unit文字材料

全新版大学英语视听阅读-Unit-文字材料————————————————————————————————作者：————————————————————————————————日期：Unit 1Watchingvideo SCRIPTNarrator: The cheetah. With an astonishing ability to sprint from zero to eighty kilometers per hour in just three seconds, it’s the fastest animal on land. At full speed, it can reach almost 100 kilometers per hour. Nothing can escape a cheetah at full sprint. Unfortunately, this beautiful, shy animal is in serious danger of becoming extinct.In order to help, National Geographic is sending a team into the Moremi Wildlife Reserve of Botswana. Their goal is to help save these magnificent creatures by capturing them on film.The city of Johannesburg, South Africa, is the final stop befor e the team’s journey into the wilds of Africa. Heading the expedition is Chris Johns, a photographer for more than 25 years. Chris has been planning this trip for a long time, and accompanying him is guide Dave Hamman. Dave has lived in southern Africa most of his life and knows the region well. His knowledge will be useful as the two men head more than 800 kilometers north into Botswana and the wonderful Okavango Delta.The Moremi Reserve is a truly magical place. It seems that Africa’s entire animal king dom resides in the region. Zebras, buffaloes, and elephants are easily viewed from the rough dirt road. Even a giraffe makes an appearance. Chris and Dave continue their drive into the evening. They need to be far into the wilderness to begin their task: finding cheetahs.Narrator: The next day, they’re up early to begin their search.Chris Johns, National Geographic Photographer: “You can’t just drive out there and order up a cheetah. It doesn’t happen like that. You know that it could take days, weeks.”Narrator: But then something incredibly unexpected occurs . . .Dave Hamman: “I don’t believe this.”Narrator: It’s a female and five of her young.Hamman: “This is just not normal.”Narrator: During all of his years in the bush, Dave has never located so many cheetahs this quickly. This is exactly what they had been hoping for. The discovery is especially promising for Chris.Johns: “Cheetahs are a metaphor for some of Africa’s conservation problems. Because cheetahs need range, and they’re a good wa y to explain to people that loss of habitat means the potential loss of species.And it’s possible that in my lifetime cheetahs could become extinct in the wild, and that’s —to me —a tragedy that’s unspeakable.”Narrator: The Moremi Wildlife Reserve has offered Chris one of the last windows into the natural world of the cheetah. It will take a while for the cheetahs to trust Chris, but if he succeeds, he knows he’ll be able to take the photographs he really wants: a shot of a cheetah pursuing and k illing its prey, or a “kill sequence.”Johns: “We know there are certain things that a cheetah story has to have. One of the most important things it has to have—which is an incredibly difficult thing to get—is a kill sequence, and you’re always looking for that picture.”Narrator: Cheetahs are capable of tremendous bursts of speed, and have the capacity to gain speed more quickly than a sports car.However, while they can reach almost 100 kilometers an hour, cheetahs can’t maintain such speeds for more than 200 to 300 meters.The cheetah’s failed to catch her dinner this time. Cheetahs must make a kill every few days. After missing the reedbuck, the mother is exhausted, and her cubs are still hungry. The two men drive back to camp, leaving the cheetah family to rest in the shade.Narrator: The next day, Chris and Dave return to where they last saw the family and find that the mother and her cubs are gone. The female has probably taken the cubs away to protect them. They must now look for the cheetahs all over again.Johns: “We still haven’t seen the mother with five cubs for several days now. The challenge is to keep your concentration, to constantly look. I mean, we’re looking for at least eight to ten hours a day.”Narrator: The tiring and difficult search turns from days into a week. The two men scan everything from heavy bushes to open grasslands, hoping to catch sight of the mother. Then, suddenly, their efforts become worth it.Hamman: “There! Let’s go, let’s go!”Johns: “Did you see her?”Hamman: “Yeah! She’s in the grass, just down, just down the break . . .”Narrator: They’ve found her and she looks fine. Chris must now wait to see if the mother cheetah will let him back into her trust so that he can photograph her. Only she can decide if and when.Chris’s opportunity for shooting a kill sequence presents itself later in the morning. Suddenly, the mother sits up, watching and listening carefully. She’s seen something: two reedbucks. Johns: “Twelve o’ clock. Two reedbucks, twelve o’ clock.”Narrator: With her cubs hidden safely away, the brave hunter moves toward her target. Johns: “There she goes! There she goes!”Hamman: “Hang on!”Narrator: The men must drive as quickly as possible in order to get the shot.Johns: “She just moved.Did you see her? Hang on. She nailed it. Got ’em! Good job, girl. Well done! She’s a good hunter. She’s a real good hunter.”Narrator: In typical cheetah style, the mother chokes her prey. Then, she takes time to recover from her sprint.Johns: “It’s a vulnerable time because if a hyena or another predator moved in on her, she could be ambushed. She is going to be very cautious.”Narrator: Satisfied for the moment that no other predators are in the area, the female calls her cubs to join her for their meal.Johns: “It’s lunchtime . . .”Narrator: The mother and cubs are finally trusting Chris more than he ever expected. Johns: “It’s amazing that the cheetahs are letting me this close. These are the pictures I’ve been waiting for for ten years.”Hamman: “You only see things like this if you’re extremely lucky, but also patient. How many hours have we spent with these cheetahs now to actually get this far? You know, you just have to put in the time to get the results.”Narrator: Finally, all of their patience has brought the expedition the results they had been waiting to achieve, but there’s still one more surprise for them . . .Each day, mother and cubs open up more to the humans, and allow them to get closer. Then finally, something truly wonderful happens.Johns: “That was a fantastic experience, for me one of the highlights of my life. But I think with that experience goes a lot of responsibility on my part.”Narrator: Chris now feels that he has a special responsibility. He wants to communicate the endangered status of these beautiful animals to the world — both through his photographs and the National Geographic article.Johns: “She’s just given me a tremendous privilege, one of the finest privileges of my life. So with that privilege goes a g reat deal of responsibility, I think, on my part.”Narrator: Hopefully, Chris can fulfill this responsibility by bringing the endangerment of these animals into worldwide focus. Maybe his actions will help save the cheetahs of the Okavango, and the world.HOME LISTENINGaudio SCRIPTUnderstanding ExtinctionA species is considered extinct when careful scientific surveys show that the last individual of that species has died. The loss of many species of plants and animals has been attributed to changes in climate, genetic weaknesses, and human activities such as hunting and environmental destruction. Studies have shown that almost all living things will eventually become extinct. In fact, more than 99 percent of the species that have ever lived on Earth have now disappeared permanently. Although this sounds like a terrible situation, it is important to understand that the earth seems to recover from the loss of great numbers of species. In many cases, replacement species emerge over time; however, extinction does decrease the diversity of life on the planet in the short term. These replacement species often require recovery periods of millions of years. Human beings have had a huge impact on the extinction rates of various species. Therefore, scientists have recently begun to examine humankind’s effects on the numbers of species that have become extinct. Through the use of geographical and biological research, a “background extinction rate” has been established. These figures show the numbers of species which have disappeared during specific time periods. By comparing rates of extinction before and after human existence, researchers were able to discover the exact effects of humankind on nature. Studies now cite that the extinction rates after human life began are 100 to 1,000 times greater than before human influence on Earth. Future rates are forecasted to be even higher. This demonstrates the tremendous negative impact that human activity is having on extinction rates.Scientists are currently researching methods of dealing with this astonishing trend. As individuals, educators, and governments try to manage species survival, one key factor they find is that without help, some of the world’s species cannot survive. In addition, scientists must learn to make difficult decisions based on incomplete information. They must also deal with groups that may have a vested interest in not protecting certain species. For example, people interested in developing oil fields in the Arctic may not think the protection of the wildlife in the region is of primary importance.Unit 2Watchingvideo SCRIPTNarrator: Near the edge of the Arctic region of Canada, the short summer is being chased away by a constant cold wind from the north. Along the western shore of the Hudson Bay, winter is beginning to close its grip. One animal, with its thick fur and layer of heavy blubber, actually thrives in these freezing, lonely surroundings: the polar bear.Cam Elliot, Manitoba Conservation: “Polar bears are built for winter. They’r e built for the cold. They’re built for the wind.”Narrator: These marine mammals spend most of their lives on frozen seas, and they depend on the frozen ice packs for hunting. But these polar bears don’t enjoy the luxury of an uninterrupted winter.Elliot: “With the onset of summer and the warmer temperatures, all of Hudson Bay melts. Unlike the high Arctic, there’s no permanent ice pack here. When the Bay melts, the bears are forced to shore.”Narrator: It’s a seasonal life for the bears and when the w eather starts to turn cold again, large numbers of them gather around the coast. At this time, these typically private animals will interact in ways not completely understood by humans, all the while waiting for the Bay to freeze so they can go back to the ice and their food source. As the bears wait, they often have company. These “tundra buggies” are designed to bring people to the polar bears.Nikita Ovsyanikow, Biologist: “Well, it’s an adult male, but rather young. He’s not in bad shape.”Narrator: No other animal hunts the polar bear; they’re at the top of the food chain. Therefore, they are considered good indicators of the health of the Arctic environment.Ovsyanikow: “What is especially attractive in polar bears in terms of conservation, it is a we ll ... we say “umbrella species”. It’s a large predator which is the top of food chains in the Arctic.”Narrator: At this time of year, the polar bears have used up the built-up fat reserves that have kept them alive since the ice melted.John Bykerk, Pol ar Bear Guide: “They’re hungry. Unless they’re lucky enough to find some dead beluga whale or dead seal, perhaps that’s washed up on shore. They’ve essentially gone four months at this point without having a bite to eat.”Narrator: Many researchers believe that the health of polar bears parallels the health of the environment. Scientists are concerned that despite the constant cold in Northern Manitoba, it may not be staying cold long enough to keep the environment stable. Global warming may be affecting t he ice patterns, which are critical for the survival of the world’s largest land carnivore.Elliot: “Over the last twenty-five years, research conducted by the Canadian Wildlife Service has found about a two-week advancement in spring weather and ice melt. Polar bears are a creature of the sea ice. When they’re out on the ice, they’re hunting seals. Anything in global climate that would affect the stability or the length of the time that the ice is on the Hudson Bay or the Arctic waters, is going to have i mmediate impact on polar bears.”Narrator: Polar Bear Guide John Bykerk is also concerned about the impact of global warming on the bears. He reports that in a recent year, ice didn’t form on Hudson Bay until around December 12th. The bay normally freezes around November 19th. As a result, the bears lost two or three weeks of feeding at the beginning of the season. He also reports that the ice thawed earlyin the spring of the next year, so the bears lost another two or three weeks. In total, the bears lost four to six weeks of hunting, which significantly affected their ability to find enough food. Narrator: Nikita Ovsyanikow has studied polar bears for years, and believes they are a key to understanding the Arctic.Ovsyanikow: “When we focus on polar bea rs, and develop any consideration measures for polar bears, the consequence of that is that we are protecting the entire Arctic ecosystem.”Narrator: For most people, polar bears truly symbolize the frozen North of our Earth. It’s hard to imagine the Arctic — or the world — without them. Can the world afford to lose the beautiful polar bear? Will people do something to ensure that they survive? The future of one of the Arctic’s most majestic creatures lies in the answers to these questions, and in the conservation efforts of a caring world.HOME LISTENINGaudio SCRIPTClimate Change: Not Only a Human WorryBy Margaret BenningNew York, June 4 In the past century, the earth’s temperature has risen by approximately 0.6 to 0.8 degrees Celsius. Scientists believe that this is the result of an enhanced greenhouse effect, which is the process by which the earth maintains its temperature. Recently, a rise in certain types of gases, such as carbon dioxide (CO2), has increased the amount of heat trapped near the earth’s surface by the effect. This increase has resulted in an insulating and warming of the planet. These problematic gases, or “greenhouse gases”, come from car and truck exhaust, factory smoke, and the burning of certain substances for heat and light. If alternative methods of producing energy are not found soon, the earth’s temperature will likely rise between 1.4 and 5.8 degrees Celsius by the end of the 21st century.Extreme temperature changes, such as those projected over the next 100 years, could be a serious threat to the human environment. However, the effects of global warming will most likely appear in animal populations first. In fact, certain changes have already been observed. For example, early thaws in the ice of the Bering Sea have affected the mating season of several types of seals. Certain species of birds are changing their nesting patterns as well. Certain plants are flowering earlier, and other large animals are changing their annual periods of sleeping and waking. According to Stanford University, global warming has directly resulted in biological changes to 1,473 species around the world.Environmental groups, both governmental and private, are currently working to decrease the amount of dangerous gases, or “emissions”, released each year. One of the first international gatherings organized by the United Nations to approach the problem produced a document which eventually became known as the “Kyoto Protocol”. Its aim was to stabilize greenhouse gas levels to prevent dangerous cha nges in the world’s climate. The agreement set limits on the amounts of greenhouse gases that each participating nation could release each year. Unfortunately, the agreement didn’t include strict enforcement procedures for implementing the program, and as of 2008, several countries only participate in the plan on a reporting basis. Others, including the United States, have refused to sign the document.Unit 3Watchingvideo SCRIPTNarrator: In a small village in Provence, France, residents have gathered to give thanks. While they sing and pray to Saint Anthony, these church members are praying for something different: a good truffle harvest. At the annual truffle mass, the collection plate is filling up, and not just with cash. In Richerenches, truffles ar e sometimes called “black diamonds”. At a price of up to $1,000 U.S. per pound, they’re one of the world’s most expensive foods.The name Richerenches means “rich earth”, appropriate for this village. Half of France’s black truffles are transported throu gh the town’s market, up to $180,000 U.S. worth a day. They’re all looking for truffles, and not just any one will do, either.Pierre-Andre Valayer, Truffle Broker: “It’s a most important market of truffles in France. So if you want to buy some truffle, yo u have to be in Richerenches to buy something. So for the sellers, it’s the same thing. If you want to sell well, they have to come to Richerenches.”Narrator: Provence generally brings to mind summer holidays, lazy afternoons, and ancient customs. In win ter though, the small town’s pace speeds up considerably. Many of the region’s farmers also work as truffle hunters. Most of the business is done discretely from the backs of the brokers’cars. One small bag of truffles is worth hundreds of U.S. dollars, so the trade is certainly lucrative.Philippe Oger, Truffle Eater: “I do think they buy apartments and so on . . . on the Riviera with this money. I know that.”Narrator: The buying and selling of truffles is mainly a cash business, it’s usually under the table. This means that the brokers often don’t pay any taxes on the money they earn and neither do the hunters.Most people presume that truffles are only an expensive luxury for the rich; however, regular people who cook at home often spend money on the m, too. France’s gourmet food companies also buy truffles from the brokers and export them to restaurants in the U.S., Japan, and elsewhere. The demand is high, but unfortunately, the supply is decreasing.Herve Poron, Truffle Exporter: “Today, if you find one hundred tons, it’s a very good production. In fact, it’s most of the time it’s more like twenty, thirty, or fifty tons ... compared to one thousand, one hundred years ago.”Narrator: The best truffles are deep black, with white veins, but there are fewer and fewer of them available these days. One major reason for the decrease could be the recent changes in Provence’s truffle-growing environment.Poron: “Because to grow truffles you need woods, and the woods have disappeared. And what is left is not often very well taken care of . . . so we’re desperate for woods. That explains the lower production today.”Narrator: Truffles grow underground, around tree roots. If there aren’t as many trees left, there are fewer places for truffles to grow. Provence is a farm region where farmers grow lavender, and grapes for the famous wines. Now only a few places remain that allow truffle growth.Truffle hunter Joel Barthelemy is looking for those places with the help of his yellow lab, Jade. Jade is a trained sni ffer dog. All dogs have sensitive noses, but sniffer dogs’ are exceptional. However, there are other factors involved.Joel Barthelemy, Truffle Hunter: “The dog has to pay attention, and he has to love his master. You can do all the training you want, but the dog has to want to please his master.”Narrator: Jade seems to have the capacity for both of these requirements. She’s found something and gets a treat for her effort. As the two hunters continue their search for truffles it seems that for today at le ast, there’s no truffle shortage here. Perhaps Saint Anthony has listened to the truffle hunters’ prayers after all.HOME LISTENINGaudio SCRIPTTruffle FarmingWhen you think about where truffles come from, you probably picture a small town in the south of France. While the French countryside does produce much of the world’s supply of truffles, other areas are fast becoming important players in this lucrative game.A Difficult UndertakingThe situation is clear: truffles can’t be grown just anywh ere. They must be grown near or under trees since scientists believe that this is what produces their distinctive flavor. It is also extremely difficult to cultivate them the way one would grow other crops. This special product doesn’t appear in the spring and summer, but emerges only in the fall and winter. Black truffles, which are the best-known of the French truffles, can be harvested only from November through March. White truffles appear only from September through early January. Furthermore, the weather conditions, such as the temperature, must be just right and the amount of rainfall must be adequate for the truffles to grow properly. Due to these challenges, very few farmers have mastered the skill of successfully planting and harvesting truffles on a regular basis.Truffles from ItalyThe world’s second best-known supplier of truffles after France is Italy. The Piedmont region near the city of Alba is the center of the Italian truffle business. There, truffles are sold in their original form and are also used in pastas, flavored olive oils, and breads. Alba is best known for its white truffles, which many people feel have a finer and more interesting flavor than black truffles. Truffles are so important in Alba that there has been a truffle festival, which lasts for several weeks, every year since 1899. Thousands of truffle lovers arrive in Alba each fall to enjoy the celebration and the scenery, and most importantly, to sample the truffles.Other Sources of TrufflesOther countries, including Spain, Sweden, New Zealand, Australia, the U.K., and the U.S. also produce truffles. Currently Australian truffle growers are working hard to increase their share of the worldwide market. Scientists there have analyzed the soils, rainfall levels, and types of trees available in order to maximize their production and produce the finest tasting truffles possible. In certain parts of Australia, growing conditions are very close to those of the south of France and production is increasing year by year.Unit 4Watchingvideo SCRIPTNarrator: Welcome to “Shark Alley”, one of the few places where great white sharks roam. Tourists often visit the coast of South Africa to see these sharks in their natural environment. Diver: “Whoa!”Narrator: But these days, the great whites are part of a large controversy. People are wondering if cage diving is turning the world’s largest predatory fish into a hunter of humans.Taryn Warner, Surfer: “There’s just started to be more and more attacks, more friends of ours, people that we actually knew.”Narrator: Is baiting the sharks conditioning these creatures to think of humans as food? Two men want to find out: biologist Brady Barr, and shark researcher Ryan Johnson. As part of his research into these huge animals, Barr plans to swim with the great whites of Shark Alley. Shark Alley is located near the town of Gansbaai on the tip of South Africa’s Cape of Good Hope. Dyer Island is located just off the coast of Gansbaai, and just off Dyer Island is a place called “Geyser Rock”, which is home to thousands of cape fur seals. Great whites often swim up and down the channel hunting the seals, which has earned this area the name “Shark Alley.”An entire tourist industry has developed here which is based on people who come to dive with sharks. Dive operators often throw fish parts and blood into the water to obtain more shark activity for their customers. But what happens if you use bait to attract sharks to humans? Do the sharks learn to think of people as food?Narrator: Ryan Johnson, a shark researcher from New Zealand is in Gansbaai to find out.Ryan Johnson, Shark Researcher: “My research really entails looking at the predatory behavior of the white shark.”Narrator: Biologist Brady Barr is going to accompany Ryan on a visit to Shark Alley. They hope to reveal more about shark behavior and the possible dangers of cage diving for swimmers and surfers. It’s early morning when Ryan and Brady get to Shark Alley. They want to be there before anyone else.Johnson: “These are design ed to sort of resemble the natural prey; the larger prey of the shark.”Narrator: Ryan plans to monitor the sharks’ behavior before the cage-dive operators arrive. He’ll then observe whether or not the arrival of the dive boats affects how aggressive the sharks are. Once the decoys are set, all they need to do is wait; but they have no idea when—or if—a shark will come.Dr. Brady Barr: “There it is! Oh my gosh! Look at that thing!”Narrator: It’s a huge great white.Johnson: “Here he comes!”Barr: “What’s he doing, what’s he doing? Oh, man, he’s huge! Look at him! He’s going to go for it! Is that him? Come on, baby! Hit it! Here he comes. Here he comes. Here he comes. Here he comes. He’s got it!”Narrator: Ryan rates each shark for aggressiveness by giving it a score from one to five. In the most aggressive attack, a huge shark hits the decoy with such force that part of its body leaves the water.Barr: “Look at the size of that thing! Look at him!”Narrator: This shark receives a rating of five out of five for aggression.Johnson: “He decided to eat it, eh? It’s going to be a long day in the workshop, now.”Narrator: The shark has made a mess of Ryan’s decoy.Johnson: “Not too bad, eh?”Narrator: As the day continues, the cage-dive operators begin to appear in Shark Alley and start baiting the sharks to encourage them to approach the cages. Will the bait cause the sharks to become more aggressive, just as the surfers fear? It takes time for the sharks to react to the arrival of the boats. So, while Ryan continues to monitor the sharks’ behavior, Brady will visit a shark-diving boat. He wants to see just how the cage-dive operators interact with the animals. Barr: “Thank you, my friend, I enjoyed it. Very good.”Narrator: The boat operators prepare the cage and start throwing bait in the water. It’s not long before a big shark appears. Now it’s Brady’s chance.Barr: “Man, that is huge. I want to get in the cage! Can I go? I’m ready! OK, I’m ready.”Dive Boat Operator: “Brady’s ready.”Barr: “I’m ready!”Narrator: Getting into and out of the safety cage is the most dangerous time for the cage diver. One slip and the diver could end up in the water with the shark. Once he’s safely inside the cage, Barr can’t see the shark. He has no idea from which direction the great white will come. Finally, the great shark swims out of the murky depths, but then disappears again into the darkness. Brady has lost sight of the large predator once again, but then suddenly . . . The shark tries to get its massive head between the bars. The attack’s over as quickly as it began. It’s a frightening experience, so Barr wants some fresh air.Dive Boat Operator: “Brady! Go down! Go down! Go down!”Narrator: The shark has silently reappeared. It’s far too dangerous for Barr to leave the cage. He’s trapped. Finally, after a few anxious moments, the shark swims away. Barr can make his escape at last.Dive BoatOperator: “Go! Go! Go!”Barr: “Woohoo! Oh, man!”Narrator: Back on the research boat, Ryan is finishing up his study regarding cage diving’s impact on sharks. He’s found that the boats do have a short-term effect on the sharks’ behavior, but it’s the opposite of what one might expect.Johnson: “I think it’s becoming clear that there is a short-term impact on their behavior, an immediate impact. When the sharks operators are there with their baits in the water and the shark has an opportunity to come up there and mouth this bait, it does seem to put them more in a scavenging mode of mind.”Narrator: Ryan argues that the sharks’ active hunting instincts may actually be switched off during cage diving. He feels it may be because dead bait is used, which could make the sharks less aggressive. Once the boats leave, the sharks go back to their normal behavior. Ryan has also developed some theories regarding the long-term effects of cage diving. He’s confident that the cage divers are not training sharks to eat people.Johnson: “I’m working with the sharks every day, and truthfully, they don’t stay in this area long. Maybe one day, two max. And no animal can be conditioned when you’ve only got that one。