It’s not easy to swim 109 miles when you’re starving to death. It’s not easy either to try to survive when you’re losing body weight at a rate of 2. 2 lb. a day. And it might be the hardest of all if you’re a nursing mom and your calorie intake has dropped so low that you can no longer produce the milk you need to care for your young.
As a newspaper in Nature Communications reveals, all of those challenges and more are facing the world’s polar bears, thanks to disappearing sea ice in our warming world, denying the animals a platform that they need to hunt for seals. If the trend isn’t reversed (扭转) soon, the estimated 26, 000 polar bears in the wild could start to lose their hold on survival before the middle of this century.
The researchers followed 20 different polar bears in Manitoba, Canada, from 2019 to 2022, fitting them with GPS trackers and video collars and periodically tranquilizing(麻醉) them to analyzes their blood, body mass, and daily energy consumption.
“The polar bears in Hudson Bay are probably at the edge of the range at which they can survive right now,” says Anthony Pagano, a research biologist with the U. S. Geological Surrey and the lead author of the paper. “Most of the modeling work suggests that around 2050, they are going to be on land and away from their primary habitat on the ice.”
According to the study, the data gathered was troubling. Weight loss varied among bears, with the daily loss of 2. 2 1b. representing an average; some of the subjects dropped up to 3. 75 lb. every 24 hours.
The bears are efficient hunters when they’ve got the purchase of ice beneath them, but they are clumsy when they are going after seals and trying to swim at the same time.
That leaves them searching on land for foods they would not ordinarily eat and getting little payoff for their efforts. Polar bears are feeding on ducks, geese, and eggs. Other foods on the desperate bears’ menus include berries and other vegetation. None of that food is as calorie-rich as seals.
1. What’s the function of the first paragraph?| A．To make a prediction. | B．To introduce the topic of the text. |
| C．To describe the greatness of mother bears. | D．To offer some advice on saving the bears. |
| A．By observing them in the wild. | B．By analyzing their blood samples. |
| C．By copying their living environment. | D．By tracking them with GPS and video collars. |
| A．They will adapt well to the changing environment. |
| B．They will develop to become better hunters on land. |
| C．They will move to other areas with more suitable habitats. |
| D．They will struggle to survive due to the loss of their habitat. |
| A．The challenges faced by polar bears. | B．The future of polar bears in the wild. |
| C．The methods used to study polar bears. | D．The importance of protecting polar bears. |
相似题推荐
【推荐1】In mainland Britain, people who has ever attempted to grow berries or nuts — or indeed feed the bird — will know, doing so is identical to an opening move in a game of chess with local grey squirrels, a game the squirrels tend to win. Grey squirrels are also fond of the occasional bird’s eggs or the young birds, and enjoy tearing and eating the bark of young broadleaf trees, which can either kill the trees or leave them open to infection. This, apart from affecting biodiversity and the landscape, harms the wood industry. The loss — in damaged timber, lost carbon revenue and tree replacements — is not insignificant: £37 a year in England and Wales.
Grey squirrels (Sciurus carolinensis), introduced from North America in 1876, have nearly replaced the native red squirrels (Sciurus vulgaris) in Britain by outcompeting them for food and habitat. They are larger, and stronger, and resistant to squirrel pox virus, while reds are not. About 3 million now live in the UK; the International Union for Conservation of Nature lists the grey squirrel among the top 100 most harmful invasive species in the world.
In Britain, significant efforts have been made to stop grey squirrels’ progress, including trapping, shooting, and releasing pine martens into their habitats. The latest move, a workable system for which was thought to be a decade away, is forbidding the breeding of grey squirrels. However, legal challenges brought so many delays that the invasive grey squirrels. population expanded to an unmanageable level and wiping out was abandoned. The main issue in Britain was thought to be more technological than legal — designing a drug that targets only grey squirrels to prevent them breeding. Another possibility in the years ahead is to use DNA editing to ensure grey females are born unable to give birth.
Obviously, there is a hint of xenophobia (仇外) in some discussions about the introduction of grey squirrels to Britain nearly 150 years ago which has had an impact on the local ecosystem, posing a threat to native species. It’s also worth noting that reds — which also tear bark and take eggs — were seen as pests until the early 1930s, and extensively killed. There is, too, a strong argument that ecosystems evolve naturally, and it may be impractical and unrealistic to intervenes or even resist it. The attraction of controlling the breeding of the grey squirrels is that it is less inhumane, and aims for balance rather than uprooting.
1. What does the author focus on in paragraph one?| A．The harm of grey squirrels. |
| B．The cutting habits of grey squirrels. |
| C．The effect of grey squirrels on the wood industry. |
| D．The game between the British and grey squirrels. |
| A．Their huge number. | B．Their unique origins. |
| C．Their breeding ability. | D．Their physical qualities. |
| A．To offer more labour. | B．To invest more money. |
| C．To perfect the law. | D．To take advantage of technology. |
| A．Unclear. | B．Indifferent. | C．Favorable. | D．Doubtful. |
【推荐2】Moments ago, a seal was resting on a piece of floating ice deep in an Antarctic channel. Then three hungry killer whales appeared. When the seal noticed them, it was already surrounded.
On this sheet of sea ice, the nearly thousand-pound sea l would be unreachable for most of his enemies in nature. But these killer whales had mastered a hunting technique called wave washing: working together to turn water into a weapon.
Having identified their target, the killer whales formed a battle line and started rushing toward the ice. Just before reaching it, they rolled to their sides in a single, synchronized (同步的) motion. The wave they created was so powerful that it flooded the ice sheet and washed the frightened seal close to the edge of the ice sheet. Slowly and methodically, they repeated the attack. At the third time, the wave sent the helpless seal flying into the sea. It struggled to climb onto a piece of ice, but then disappeared from view...
“The level of intelligence that went into making each wave was staggering. They solved the problem with very complex teamwork. They used water as a tool,” said wildlife filmmaker Bertie Gregory, who had spent a decade tracking those killer whales, known as Bls. “I rarely saw failed hunts. This behavior was not what they were born with. It was learned and mastered over decades. Every time they made waves, it almost felt like more of a teaching experience than hunting. It was terrifying to watch.”
But as Antarctica warms and sea ice disappears, seals are increasingly staying on land, out of killer whales’ reach.
“I’ve found Bls are losing about 5 percent of their population every year. Whether this subgroup will go extinct or just adapt their behavior, I don’t know,” said Gregory. “But with fewer opportunities for the killer whales to wave wash, I’m seeing an extinction of a culture.”
1. How did the killer whales get the seal on the ice sheet?| A．By making huge waves. | B．By jumping onto the ice sheet. |
| C．By destroying the ice sheet. | D．By waiting underwater patiently. |
| A．Puzzling. | B．Shocking. | C．Satisfying. | D．Annoying. |
| A．The seals and killer whales. | B．The rising sea level. |
| C．The loss of a hunting skill. | D．The disappeared ice sheet. |
| A．It is a natural behavior with whales. | B．Usually, the smartest whales can learn it. |
| C．It can be carried out by one whale alone. | D．Perhaps, it is only mastered by certain groups. |
【推荐3】Dogs may understand more than they show. Pet dogs’ brains displayed neural (神经的) signs of surprise when their owners showed them an unexpected toy. The findings, published March 22 in Current Biology, suggest that dogs create mental concepts of objects.
“Anyone who has ever interacted very much with a dog probably is not that surprised to know that dogs understand that your speech is referring to at least a few common objects,” says Ellen Lau, a neuroscientist at the University of Maryland in College Park. But some people may have assumed this “understanding” is a simple reaction to the sound of the word.
Marianna Boros, a neuroscientist at Eotv’s Lorand University in Budapest, recruited 27 pet dogs and their owners. The team asked the owners to bring five familiar toys and other objects to the lab. Researchers stuck electrodes (电极) to the dogs’ heads and gave them two tasks: lieon a mat and stay awake.
Every so often, a dog would hear a recording of its owner saying things like, “Kun-Kun, look, the ball!” The dog’s owner was on the other side of a wall with a window covered by the curtains. Just after the recording played, the curtains were opened, showing the owner holding a toy—the ball or a different toy, such as a rope.
Just after seeing an unexpected object, an electrode monitoring (监测) brain activity picked up a larger-than-normal signal. This signal indicates surprise, the team says, and suggests that the dog had already formed a mental concept and expectation of the ball after hearing that word. In fact, the signal was especially strong for a mismatch involving words that the dogs reportedly knew very well. “That suggests that it is really about understanding and knowledge of the word,” Boros says.
1. Which statement best reflects Ellen Lau’s view on dogs’ understanding of speech?| A．Dogs understand speech primarily as a reaction to the sound of words. |
| B．Dogs understand speech, especially when it involves common objects. |
| C．Dogs have limited understanding of speech, mainly reacting to tone. |
| D．Dogs shows understanding of the deeper meaning of the speech. |
| A．By monitoring their brain activity. | B．By observing their behaviors. |
| C．By playing recordings. | D．By opening the curtains. |
| A．Dogs hear commands. | B．Dogs display behaviors. |
| C．Dogs show interest. | D．Dogs form expectations. |
| A．Examining Dogs’ Hearing of Words | B．Revealing Dogs’ Mental Concepts |
| C．Exploring Dogs’ Reactions to the Orders | D．Studying Dogs’ Neural System |
【推荐1】Robots have always imitated life. Social androids powered by artificial intelligence have now reached a level where they may be ready to work in shops, airports, and care homes. But an entirely new class of robots is being developed that can grow, evolve, and even reproduce.
Growth is a new frontier in robotics. Scientists are using plant biology and mechanics to design robots that grow like roots or vines to move around obstacles and carry objects.
Stanford University’s vine robot is a simple yet complicated plastic tubular (管状的) robot that grows by unfolding from the inside as air is pumped into it. The soft body can move over rough or sticky surfaces littered with sharp objects, grow to 100 times its original length, and squeeze through gaps one-quarter of its size.
Vine robots can twist and turn in any direction to move through tight spaces. Its designers say the flexible robot could be used to detect people and deliver equipment inside collapsed buildings or be shrunk down to work as an instrument in medical procedures.
Robots that reproduce to make exact copies of themselves are ready to take that progress up a level. Reproduction and evolution were actually used in an earlier experiment in 2015. European scientists built a computerized ‘mother’ robotic arm that assembled smaller robots. Each generation that the system built became progressively better at moving.
It was a major milestone in robot learning and was used as inspiration for robotic evolution projects at the UK York Robotics Laboratory.
Designs are tested in a model of a nuclear reactor, where robots must clear radioactive waste. Each robot is scored on its success at the task, and the computer then chooses which robots are allowed to reproduce. What form that robot life takes depends entirely on its success.
Researchers say their system could operate entirely by itself. But future evolutionary robot systems would likely need a kill switch to stop the system from running out of control and harming humans or the environment.
1. What does the underlined word most probably mean in the second paragraph?| A．Boundary. | B．Field. | C．Question. | D．Technology. |
| A．It can squeeze through gaps one fifth of its size. |
| B．It can operate on patients in medical procedures. |
| C．It can move over smooth surfaces littered with sharp objects. |
| D．It can spot people and take equipment inside destroyed buildings. |
| A．By choosing the robots to reproduce. |
| B．By operating entirely by itself. |
| C．By clearing radioactive waste successfully. |
| D．By stopping the system running out of control. |
| A．Robots Imitate Life to Create Better Versions of Themselves |
| B．Artificial Intelligence Have Now Reached a High Level |
| C．Vine Robot can be Used in Many Different Situations |
| D．Scientists are Using Plant Biology and Mechanics to Design Robots. |
【推荐2】Are your teeth fit? Are you too lazy to brushthem? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone.
The Kolibree toothbrush was shown at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.
The toothbrush will be able to teach you to brush right (don’t forget the insides of the teeth!) and make sure you’re brushing long enough. “It’s kind of like having a dentist actually watch your brushing on a daily basis,” says Thomas Serval, the French inventor.
The toothbrush will also be able to talk to other applications on your phone, so developers could, for example, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. “We try to make it smart but also fun,” Serval says.
Serval says he was inspired by his experience as a father. He would come home from work and asked his kids if they had brushed their teeth. They said “yes”, but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.
The company says the Kolibree will go on sale this summer, for $99 to $199, depending on features. The U.S. is the first target market.
Serval says that one day, it’ll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.
1. Which is one of the advantages of the Kolibree toothbrush?| A．It can help users recover their phones. |
| B．It can track users’ school performance. |
| C．It can sense how users brush their teeth. |
| D．It can remove users' fear of seeing a dentist. |
| A．You will find it enjoyable to see a dentist. |
| B．You should see your dentist on a daily basis. |
| C．You can brush with the Kolibree as if guided by a dentist. |
| D．You’d like a dentist to watch you brush your teeth every day. |
| A．How Serval found out his kids lied to him. |
| B．What inspired Serval to invent the toothbrush. |
| C．How Serval taught his kids to brush their teeth |
| D．Why Serval thought brushing teeth was necessary. |
| A．They were unwilling to brush their teeth. |
| B．They often failed to clean their toothbrushes. |
| C．They preferred to use a toothbrush with a dry head. |
| D．They liked brushing their teeth after Serval came home. |
【推荐3】They are probably the longest-standing and biggest rivals (对手) in international sport— Chinese badminton player Lin Dan, with his deadly smashes (扣球) and drop shots, and his Malaysian rival Lee Chong Wei, who is known for his spirit and determination.
Over the years, the two have competed with each other many times, and both have experienced victory and defeat. But Lin beat Lee the first two times they faced each other in the Olympic Games—in Beijing in 2008 and then in London in 2012.
And that was inadmissible for Lee. In fact, according to BadmintonBlaze.com, Lee once said that if he had the choice between winning an Olympic gold and beating Lin, he would absolutely choose victory over his old rival.
And he eventually did, at the 2016 Rio Games. When he beat Lin that day, Lee dropped to the floor, covered his face with his hands and looked around the stadium like a gold-medal moment although Lee eventually lost out in the final to another Chinese player, Chen Long.
All the years of trying to outdo each other have not only driven Lin and Lee to surpass (超越) themselves as players, but also developed a special friendship between the two.
They care for and encourage each other. They invited each other to their own weddings. And right before this year’s Malaysia Open, Lee, who wasn’t able to compete there on account of his nose cancer, wrote on social networking site Facebook, “My friend Lin Dan, you have my best wishes for this Malaysian Open. If I were to hope for a non-Malaysian to win the men’s singles title, I hope that it’s you my friend, my greatest rival.”
Lin and Lee are now pushing 36 and 37 respectively—ages by which most athletes would have retired—but they are planning to compete at the 2020 Tokyo Olympic Games, in the hope that they can play each other once again.
It’s as Badminton Association of Malaysia vice president David Wee once said of the two, “they bring out the best in each other”.
1. Which phrase can best describe their relationship?| A．Familiar strangers. | B．Friends and enemies. |
| C．Colleagues and rivals. | D．Teammates and competitors. |
| A．Unacceptable. | B．Inescapable. |
| C．Unexpected. | D．Impossible. |
| A．He mistakenly believed he had won the gold medal. |
| B．He was confident to defeat Lin Dan next time. |
| C．He didn’t care about the Olympic gold medals. |
| D．He took his victory over Lin most seriously. |
| A．Lin ranks second to Lee in the world badminton. |
| B．Lin is sure to compete against Lee at the 2020 Olympics. |
| C．Lee has no intention to quit playing badminton in spite of his nose cancer. |
| D．Lee wished Lin to win the men’s singles title in this year’s Malaysia Open. |
