1 . For the longest time, the predominant description about renewable energy featured awkward technologies, high costs, and burdensome allowance. In the
But now that these technologies have come of age, a new story is being written. Around the world, businesses, governments, and households are taking advantage of more cost-effective low-carbon technologies.
As in any rapid transition, a full understanding of what is happening has
To be sure,
As the green transition comes of age, it will offer solutions to all of humanity’s energy needs, placing a clean, prosperous and secure low-carbon future well within reach. Yet even as we hug
| A．license | B．absence | C．application | D．promotion |
| A．invisible | B．unbelievable | C．inevitable | D．unaffordable |
| A．Instead of | B．Owing to | C．In case of | D．According to |
| A．resources | B．revolutions | C．prospects | D．priorities |
| A．caught up with | B．compared with | C．taken place of | D．fallen behind |
| A．relevant | B．inferior | C．synthetic | D．experimental |
| A．mixture | B．caution | C．conflict | D．approval |
| A．in case | B．so that | C．even though | D．the moment |
| A．significance | B．invention | C．happiness | D．progress |
| A．dramatically | B．economically | C．independently | D．equivalently |
| A．interaction | B．modernization | C．motivation | D．transformation |
| A．natural | B．potential | C．positive | D．original |
| A．influence | B．optimism | C．estimation | D．extension |
| A．starting | B．failing | C．emerging | D．continuing |
| A．sustainable | B．traditional | C．available | D．industrial |
| A. collectively B. engine C. convinced D. contribute E. distribute F. envisioned G. address H. increasingly I. seemingly J. engagement K. initiative |
Ocean plastic has become a defining problem of our time, and a challenge to the world’s brightest thinkers and innovators. With a significant portion of plastic waste entering through rivers, the Alliance to End Plastic Waste is supporting the work of Renew Ocean to
Research published in Environmental Science & Technology in 2017 shows that rivers
Renew Oceans is part of the Renewology partnership, a brainchild of Priyanka Bakaya. Growing up in Australia, Bakaya became fascinated by science, chemistry, and the environment. Trips to India as a child
How does Renew Oceans plan to tackle a(n)
3 . Back in 2015 my colleague Adam Frank of the University of Rochester and I were having lunch near Columbia University's campus in New York City. As at Fermi's lunch 65 years earlier, the conversation was about the nature of spacefaring species. And inspired by Fermi's mental calculation, we were trying to craft an investigative strategy that made the fewest possible unsubstantiated assumptions and that could be somehow tested or constrained with real data. At the center of this exercise was the simple thought that waves of exploration or settlement could come and go across the galaxy, with humans happening to come into being in one of the lonely periods.
This idea relates to Hart's original fact: that there is no evidence here on Earth today of extraterrestrial（外星的）explorers. But it goes further by asking whether we can obtain meaningful limits on galactic（星系的）life by constraining the exact length of time over which Earth might have gone unvisited. Perhaps long, long ago extraterrestrial explorers came and went. A number of scientists have, over the years, discussed the possibility of looking for artifacts that might have been left behind after such visitations of our solar system. The necessary scope of a complete search is hard to predict, but the situation on Earth alone turns out to be a bit more manageable. In 2018 another of my colleagues, Gavin Schmidt of NASA's Goddard Institute for Space Studies, together with Adam Frank, produced a critical assessment of whether we could even tell if there had been an earlier industrial civilization on our planet.
As fantastic as it may seem, Schmidt and Frank argue—as do most planetary scientists—that it is actually very easy for time to erase essentially all signs of technological life on Earth. The only real evidence after a million or more years would boil down to isotopic or chemical stratigraphic anomalies—odd features such as synthetic molecules, plastics or radioactive fallout. Fossil remains and other paleontological markers are so rare that they might not tell us anything in this case.
Indeed, modern human urbanization covers only on order of about 1 percent of the planetary surface, providing a very small target area for any paleontologists（古生物学家）in the distant future. Schmidt and Frank also conclude that nobody has yet performed the necessary experiments to look exhaustively for such non-natural signatures on Earth. The bottom line is, if an industrial civilization on the scale of our own had existed a few million years ago, we might not know about it. That absolutely does not mean one existed; it indicates only that the possibility cannot be completely eliminated.
1. The word “unsubstantiated”（in paragraph 1）is closest in meaning to ________.| A．unconscious | B．unknown | C．unnatural | D．unsupported |
| A．No other species have ever settled on Earth except human beings. |
| B．Extraterrestrial explorers come and go at increasingly short intervals. |
| C．No spacefaring species have visited the Earth since humans emerged. |
| D．Extraterrestrial explorers once built an industrial civilization on Earth. |
| A．turn to isotopic or chemical stratigraphic anomalies |
| B．find as many signs of technological life as possible |
| C．unearth more fossil remains than we do now |
| D．leave behind synthetic things like plastics |
| A．Human urbanization should be expanded for the sake of research. |
| B．We cannot say for sure that no civilization existed before ours. |
| C．Non-natural signatures on Earth have been studied exhaustively. |
| D．An industrial civilization came into being a few million years ago. |
4 . Hibernation is a complex solution to a simple problem. In winter, food is scarce. To survive this seasonal starvation, animals, such as the arctic ground squirrel and black bear, hibernate so that physiological shifts keep them alive despite the lack of food, water and movement. Researchers and doctors alike are interested in how these hibernation tricks could help humans with their own health.
THREAT: Stroke
INSIGHT: Blood flow in the brain of a hibernating arctic ground squirrel drops to a tenth of normal. Typically such oxygen shortage would cause a stroke. But these squirrels can survive all winter because their metabolism lowers to 2 percent of its summer rate—requiring much less oxygen to maintain. If doctors could similarly lower the metabolism of a human patient immediately after a stroke—perhaps by cooling the body—they might prevent permanent brain damage, says Brian Barnes, a biologist at the University of Alaska Fairbanks.
THREAT: Diabetes
INSIGHT: People who gain a lot of weight often stop responding to insulin, which regulates the amount of glucose that cells take up from the blood. Yet grizzly bears gain 100 pounds or more each autumn and somehow avoid diabetes. A recent study found that the grizzlies' fat cells become more sensitive to insulin as they prepare for the winter, allowing the bears to keep processing and storing sugar. Scientists at biotechnology company Amgen are now testing whether making slight changes to the same protein that controls sensitivity in diabetic humans could have similar results.
THREAT: Osteoporosis
INSIGHT: If a human were to lie still for long periods without food, his or her bones would slowly degrade. A black bear, however, emerges from its cave after winter just as strong as ever because its bone is recycled at 25 percent of normal levels during hibernation. Researchers at Colorado State University are now trying to identify the hormones that control this extreme limit on bone turnover. They aim to create a drug for people at risk for osteoporosis that similarly protects bone density.
THREAT: Heart Disease
INSIGHT: During heart surgery, a patient becomes short of oxygen when the heart stops beating. To cope, the body switches from aerobic to anaerobic metabolism. Unfortunately, the change creates lactic acid, which can kill cells if it builds up. Damage of this kind does not occur in hibernating arctic ground squirrels, likely because they break down more fats than sugars even after the heart has slowed to just one beat per minute. Researchers at Duke University and the University of Alaska Fairbanks are now working to identify how this species prioritizes fat as fuel in low-oxygen conditions. Finding a way to get heart surgery patients to do the same may reduce injury to organs during procedures.
1. What is the passage mainly about?| A．What humans can learn from animals that sleep for months on end. |
| B．What health threats humans are facing while they are under treatment. |
| C．How humans can survive from the same tough conditions as animals do. |
| D．How health threats can be avoided if humans are with certain animals. |
| A．stroke | B．diabetes | C．osteoporosis | D．heart disease |
| A．Metabolism usually consumes a small amount of oxygen. |
| B．Fat cells are less sensitive to insulin than other cells. |
| C．Lying still for a long time will affect bone density. |
| D．Doctors are seeking ways to keep patients' hearts beating in surgery. |
5 . Most animal species in the world have developed some sort of natural camouflage that helps them find food and avoid attack. The specific nature of this camouflage varies considerably from species to species.
Camouflage develops differently depending on the physiology and behavior of an animal.
An animal's environment is often the most important factor in what the camouflage looks like. The simplest camouflage technique is for an animal to match the "background" of its surroundings.
Since the ultimate goal of camouflage is to hide from other animals, the physiology and behavior of an animal's predators or prey is highly significant.
In addition to background-matching coloration, many animals have distinctive designs on their bodies that serve to conceal them. These designs, which might be spots, stripes or a group of patches, can help the animal in a couple of ways. First, they may match the pattern of "the model", the background of the animal's surroundings. Second, they may serve as visual disruptions. Usually, the patterns are positioned out-of-line with the body's contours (外形).
Other animals use a more aggressive sort of mimicry. Several moth species have developed striking designs on their wings that resemble the eyes of a larger animal. The back of the hawk moth caterpillar actually looks like a snake head, a frightening visage for most predators he moth would come across.
Mimicry is a different approach than ordinary camouflage, but it works toward the same end. By developing a certain appearance, an animal species makes itself a harder target for predators and a sneakier hunter for prey. As animal species evolve, they become more and more in tune with their environment.
| A．Often, these sorts of adaptations are more effective survival tools than an animal's more aggressive weapons of defense (teeth, claws, beaks). |
| B．This disruptive coloration is particularly effective when animals in a species are grouped together. |
| C．For example, an animal that swims in large schools underwater will develop different camouflage than one that swings alone through the tees. |
| D．An animal will not develop any camouflage that does not help it survive. |
| E．In this case, the various elements of the natural habitat may be referred to as the "model" for the camouflage. |
| F．That is, the pattern seems to be a separate design superimposed on top of the animal. |
6 . The lives of sea turtles begin on a beach when hatchlings crawl up out of their sandy nests and try to get to the sea as fast as they can. Those that aren’t eaten by killers on their way to the water swim out into the ocean until they find somewhere they can hide, eat and grow.
Ten to fifty years later, depending on the species, the sea turtles mate in shallow waters. Then the females return to the same beach where they were born to lay their eggs, and the cycle begins again.
SAVE ENDANGERED SEA TURTLES! Here’s how YOU can make a difference! 1. Only buy ethically harvested seafood. Seafood Watch. org's app will help you choose seafood providers who don't harm sea turtles. 2. Use reusable bags and water containers.Reduce your use of plastics and refuse to use plastic bags, disposable straws and water bottles. 3. Volunteer for beach clean-up activities. Help make our coastlines safer for sea turtles by removing harmful garbage like plastic bags and disposable straws. 4. Clear the beach of obstacles at night. Remove chairs and sandcastles and turn off any lights so sea turtles can more easily travel between their nests and the water. |
Turtles that successfully avoid the numerous threats to their existence can live up to 100 years. But predators, fishing nets and garbage are major problems, and only one out of every 1,000 hatchlings will reach adulthood. There are seven sea turtle species, and six of them are either threatened, endangered or critically endangered. Many organizations around the world are working hard to ensure that sea turtles will not disappear from our oceans.
1. After leaving their nests, how long will it be before the sea turtles are old enough to reproduce?| A．Ten to fifty months, depending on environmental factors |
| B．Six months, if they can survive that long in the open ocean |
| C．One to five weeks, depending on how much they find to eat |
| D．One to five decades, depending on the kind of sea turtle |
| A．Water pollution that harms sea turtles |
| B．Fishing industry practices that harm sea turtles |
| C．Other animals that eat sea turtles |
| D．Turtle overpopulation that makes food short |
| A．It gives the turtles a clear path from their nests to the ocean. |
| B．Tourists won’t trip on anything in the dark when they’re looking for turtles. |
| C．Waste on the beach ruins the view at night. |
| D．It makes it more difficult for killers to hunt the turtles. |
7 . In the 1966 science-fiction movie One Million Years B. C., the movie characters had a time travel and arrived in an ancient landscape inhabited by dinosaurs and early humans. The movie was low on science and high on fiction: by then dinosaurs were long dead and modern humans were millions of years away.
A more accurate picture of Earth’s inhabitants at the time is now being revealed. In research published in Nature, a team of scientists led by Anders Gotherstrom at the University of Stockholm, and Love Dalen at the Centre for Palaeogenetics (古遗传学), also in Sweden, describe sequencing (测序) DNA samples from mammoths (猛犸象) that lived and died in north-eastern Siberia around a million years ago.
The team’s work represents a new record, for their mammoth DNA is, by some half a million years, the oldest ever successfully reconstructed. Extracted (提取) from horses, bears and even Neanderthals and Denisovans, two close cousins of modern humans, such ancient DNA has proved an invaluable tool for investigating the past. Although fossils preserve the basic physical features of extinct animals, they are silent about many crucial details that even an incomplete genome (基因组) can help to fill in.
The trouble with DNA is that it breaks down after death. The more broken down it is, the harder it is to sequence. Scientists think that, after about 6m years, all that would be left would be individual base pairs (碱基对), the equivalent of trying to reconstruct a book from several letters. Under the right conditions, however, such as the extreme cold of Arctic permafrost (冻土层) this decay can be slowed.
Dr. Dalen and his colleagues were interested in three mammoth molars (臼齿) extracted in the 1970s from Siberian geological layers that suggested great age. Samples from each were sent to Dr. Dalen’s laboratory in 2017. Having checked they had not been contaminated by bacteria or the shaking hands of Paleontologists, the DNA were extracted, sequenced, and dated. Whereas DNA samples from a living animal can run to several hundreds of thousands of letters, the ancient mammoth samples yielded merely dozens of letter long. This is close to the limit of what is scientifically usable, says a biologist named Ludovic Orlando.
1. What does the underlined word “contaminated” probably mean?| A．Protected. | B．Polluted. | C．Estimated. | D．Discovered. |
①the limited number of DNA in mammoth samples
②the break-down of mammoth’s DNA after death
③the wide spread of mammoth samples
④the damage done to the mammoth samples from external environment
⑤the difficulty in extraction of the mammoth’s DNA
| A．①②④ | B．②④⑤ | C．②③④ | D．①③④ |
| A．The fact that DNA can break down makes it easier to sequence. |
| B．The incomplete genome can’t give any details of the extinct animals. |
| C．Mammoths’ DNA samples are invaluable for their extremely long history. |
| D．The research team created a new record for reconstructing an ancient book. |
| A．The movie One Million Years B. C revealed the early human civilization. |
| B．Scientists have uncovered the secrets of life by studying mammoths’ DNA. |
| C．The mammoths’ DNA may give a clearer picture of ancient inhabitants on earth. |
| D．Discoveries of mammoths’ DNA samples help the development of DNA reconstruction technology. |
8 . Most people think of zoos as safe places for animals, where struggles such as difficulty finding food and avoiding predators don’t exist. Without such problems, animals in zoos should live to a ripe old age.
But that may not be true for the largest land animals on Earth. Scientists have known that elephants in zoos often suffer from poor health. They develop diseases, joint problems and behavior changes. Sometimes, they even become unable to have babies.
To learn more about how captivity (监禁) affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands. Zoos keep detailed records of all the animals in their care, documenting factors such as birth dates, illnesses, weight and death. These records made it possible for the researchers to analyze 40 years of data on 800 African and Asian elephants in zoos across Europe. The scientists compared the life spans of the zoo-born elephants with the life spans of thousands of female wild elephants in Africa and Asian elephants that work in logging camps (伐木场), over approximately the same time period.
The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild counterparts who died of natural causes lived an average of 56 years — more than three times as long. Female Asian elephants followed a similar pattern. In zoos, they lived 18.9 years, while those in the logging camps lived 41.7 years.
Scientists don’t yet know why wild elephants seem to live so much better than their zoo-raised counterparts. Georgia Mason, a biologist at the University of Guelph in Canada who led the study, think stress and obesity (肥胖) may be to blame. Zoo elephants don’t get the same kind of exercise they would in the wild, and most are very fat. Elephant social lives are also much more different in zoos than in the wild, where they live in large herds and family groups.
Another finding from the study showed that Asian elephants born in zoos were more likely to die early than Asian elephants captured in the wild and brought to zoos. Mason suggests stress in the mothers in zoos might cause them to have babies that are less likely to survive.
The study raises some questions about acquiring more elephants to keep in zoos. While some threatened and endangered species living in zoos reproduce successfully and maintain healthy populations, that doesn’t appear to be the case with elephants.
1. According to the first two paragraphs unlike other zoo animals, zoo elephants ________.| A．have difficulty eating food. | B．live to a ripe old age. |
| C．are not afraid of predators. | D．develop health problems. |
| A．They compared zoo elephants with wild elephants. |
| B．Zoos kept detailed records of all the elephants in the wild. |
| C．They analyzed the records of the elephants kept in zoos. |
| D．The zoo-born elephants they studied are kept in European zoos. |
| A．Female elephants live longer than male elephants. |
| B．Female zoo elephants live longer than their wild counterparts. |
| C．Female zoo elephants die much earlier than their wild counterparts. |
| D．Elephants in zoos and those in the wild enjoy the same long life spans. |
| A．It may not be a wise policy to keep elephants in the zoo. |
| B．Elephants are no longer an endangered species. |
| C．Zoo-born elephants should be looked after more carefully. |
| D．Zoos should keep more animals except elephants. |
China's Worst Sandstorm
China's worst sandstorm in a decade caused mass disruptions on Monday as vast swathes (广大地区) of the country were thrown into a thick, orange haze of dust and sand,
In Beijing, poor visibility paralyzed traffic as residents posted photos of skyscrapers seemingly
Beijing and 23 other cities recorded “off the chart”levels of air pollution, according to state media. In Beijing, PM 10, a measure of tiny particles in the air often
Officials in neighboring Mongolia, after the sandstorm
China's National Meteorological Center said it expected 12 provinces and municipalities — an area covering about 160, 000 square miles, about the size of California —
In the past two hundred years, people have caused many kinds of animals to die out. People keep building houses and factories in fields and woods. As they spread over the land, they destroy animals’ homes. If animals can’t find a place to live, they die out. Sixteen kinds of Hawaiian birds have become extinct for this reason. Other animals, such as the Florida Key deer, may soon die out because they are losing their homes. Hunters have caused some animals to become extinct, too. In the last century, hunters killed all the passenger pigeons in North America and most of the buffaloes（水牛）.
Pollution is killing many animals today, too. As rivers become polluted, fish are poisoned. Many die. Birds that eat the poisoned fish can’t lay strong, healthy eggs. New birds aren’t born. So far, no animals have become extinct because of pollution. But some, such as the bald eagle （白头鹫）and the brown pelican（鹈鹕）, have become rare and may die out.
Scientists think that some animals become extinct because of changes in climate. The places where they live become hotter or cooler, drier or wetter. The food that they eat cannot grow there anymore. If the animals can’t learn to eat something else, they die. Dinosaurs （恐龙）may have died out for this reason.
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