Of all the continents, the most drastic reduction in wildlife has occurred in North America, where the transition from a rural to a highly industrialized society has been most rapid. Among the victims are birds, mammals, and fish. We will never again see the passenger pigeon or the eastern elk. They have been wiped out. Of many other species, only a few representatives still survive in the wild. The U.S. Department of the Interior has put no fewer than 109 species on the endangered species list. (An endangered species is one with poor prospects for survival and in need of protection.) This list includes everything from the timber wolf to the whooping crane. Even the bald eagle, our national symbol, is threatened.
Animals that kill other game for food are called predators. The predators include the wolf, mountain lion, fox, bobcat, and bear. Attack against these animals began with the arrival of the first European settlers, who wished to protect their livestock. Eventually, a reward was offered to hunters for every predator that was killed. This reward is called a bounty. Ironically, the Federal government is the chief funder of predator-control programs.
The settlers also brought with them their Old World fears and superstitions concerning predators.Whether preying on livestock or not, predators were shot on sight. This attitude continues to this day for coyotes, eagles, foxes, mountain lions, and bobcats, and is largely responsible for placing the eastern timber wolf, grizzly bear, and bald eagle on the endangered species list.
Yet every animal, including the predator, has its place in nature's grand design. Predators help maintain the health of their prey species by eliminating the diseased, young, old, and injured. Predators like the mountain lion and the wolf help to keep the deer herds healthy. Their kill also provides food for scavengers that feed on carrion. Occasional loss of livestock must be weighed against the good these animals do in maintaining the balance of nature.
Overhunting an animal is an obvious form of extermination, but there are more subtle processes that often have the same fatal result. One of these is destruction of habitat. When farmers introduced sheep and cattle to North America, the domestic animals competed with the wild animals for the available grazing land. Animals like the buffalo and the pronghorn antelope, which once roamed the plains in countless numbers, were either killed or pushed off the grasslands. Today, a few remnants of these giant herds are protected from hunters in national game preserves and wildlife refuges.

A.Eastern elk can only be seen in North America

B.Passenger pigeons are quite effective in transiting information

C.North America has witnessed the fastest disappearing of wildlife

D.The U.S. Department of State has published an endangered species list

A.animals that kill and eat other animals

B.animals that people keep on their farms

C.animals that people hunt for food or sport

D.animals that attack wolves to steal food from them

A.Bounty hunters were responsible for the predator-control programs

B.Hunters who killed predators were offered a sum of money as bonus

C.The Federal government established a foundation to protect predators

D.The settlers used to hunt predators, tame them and keep on their farms

A.they can make food for livestock

B.they can help other animals to eat healthily

C.they help to keep their prey species healthy

D.they help to feed the young and injured animals

A.Modern civilization is threatening the survival of wild animals

B.The habitat for the giant herds of buffalo is properly protected now

C.There is fierce competition between domestic animals and wild animals

D.Most people have already recognized the importance of animal protection

You don't have to be a botany expert to decipher what it means when somebody sends you a rose. Every year on Feb.14, millions of people exchange the flower to express their love——and an estimated 250 million roses were produced for Valentine's Day in 2018, according to the Society of American Florists.
But the rose's life as a symbol didn't begin with romance. In Victorian England, women's roles in society were limited by custom and norms. Within those strictures, learning the language of flowers ——the notion that each and every flower has its own meaning—— was one activity deemed domestically appropriate for them. And for ladies in that situation, its communicative possibilities also held an appeal that other domestic arts lacked; “the possibility that some women sought methods of covert communication and expression exists,” Mary Brooks wrote in Silent Needles, Speaking Flowers.
The early popularization of this practice is credited to Lady Mary Wortley Montagu, the wife of a British ambassador to Turkey in the 18th century.Enthralled by a Turkish version of flower language, Lady Montagu wrote a series of letters home to England in 1716. She described the Turkish tradition as a way of assigning meaning to objects in order to send secret love letters. Montagu's letters, published in 1763, wrote of her perceptions of this practice: “There is no color, no flower, no weed, no fruit, or herb that has not a verse belonging to it: and you may quarrel, criticize, or send letters of passion, friendship, or courtesy, or even of news, without ever inking your fingers,” she wrote. But the Lady was actually incorrect in her interpretation.
In spite of Montagu's misunderstanding, word of the concept spread. Langage des fleurs, a dictionary for the language of flowers by Charlotte de Latour, was published in France in 1819, a century after Montagu's discovery. Nine editions of the English translation of the book, which alphabetically defined each flower, were printed within three decades of its publication. De Latour's translated Language of Flowers covered most popular flowers we buy, sell and give today, from the mistletoe's importance during Christmas to the musk rose's symbolization of“capricious beauty".
In de Latour's chapter on the rose, the flower is not only defined as meaning “love”, but the plant itself is romanticized.“Who that ever could sing has not sung the Rose! The poets have not exaggerated its beauty, or completed its panegyric,” she wrote. Nature seems to have exhausted all her skill in the freshness, the beauty of form, the fragrance, the delicate color, and the gracefulness which she has bestowed upon the Rose.

A.make a decision

B.represent a message in code

C.conduct an action

D.discover the meaning of something

A.an appropriate activity for women in Victorian England

B.a way to express their romantic ideas explicitly

C.a symbol of romantic lifestyle

D.a kind of domestic art form

A.She was the British ambassadress to Turkey in 1716

B.She had a clear and correct understanding of flower language

C.She wrote a book about the language of flowers in the 18th century

D.She thought almost all feelings could be conveyed without a word

A.The beauty of rose is usually exaggerated by poets and singers

B.Roses are the essential decorations during the Christmas season

C.Rose is finally romanticized in de Latour's dictionary of flower language

D.Nowadays, it's very common for us to buy and give roses to our friends

A.Flower and Its History

B.Rose and Its Language

C.The Culture of Flowers

D.The Portrait of Roses

The cities of the world are sick. As the coronavirus pandemic continues, people living in metropolitan areas have been among the worst hit, unable to socially distance effectively and sometimes plagued with preexisting conditions that their cities helped create. Many municipalities weren't built with highly transmissible infectious disease——or human health——in front of mind, and the toll of Covid-19 is making that oversight all too clear.
The Covid-19 pandemic is a chance to focus that attention on what can——and should——be changed, to reevaluate the way cities are built, maintained, and lived in. In the midst of this crisis, some cities have already begun doing so by closing roads to cars to create room for bicyclists and socially distanced pedestrians, or by building additional hospitals and homeless shelters. These stopgap, reactive steps are important and needed, but they will do little to slow or stave off this pandemic or help prevent the next one. To ward off the outbreaks of the future, it's time to start thinking proactively, and long-term.
The best way to stop a pandemic is to never let it start. The majority of infectious diseases, including those responsible for pandemics, started out as animal pathogens (病原体). Generally speaking, these diseases don't spring from wild animal populations to humans, either. They evolve from pathogens impacting domesticated animals: the avian flu (bird flu) from poultry; MERS likely from camels; swine flu, from, well, swine. There's less consensus about the actual origin of the 1918 Spanish flu pandemic, but everyone agrees it was cross-species transmission, whether birds, swine, or horses were the culprit. But, according to James Spencer, who studies city planning at Clemson University and has conducted research on avian influenza, it's not viruses that jump hosts in purely rural areas that go on to become pandemics. “If we want to prevent these things,” he says,“we have to do a better job of managing the extremely rapid changes going on where agriculture and urbanization are happening in the same space.”
The technical term for these areas is peri-urban, places that are integrating with a developed city while still keeping a foot in the agricultural world. They are especially common in rapidly urbanizing countries. When Spencer was studying avian influenza in Vietnam, he found it wasn't the places that either totally lacked water and sewage systems, or the ones that had already developed them, that had seen the most destructive spread of the virus. It was the places beginning to construct their basic infrastructure.“My initial take on this is, if you can get those basic things right, and plan them out well, [spread of disease] can be minimized,” he says. “Not just the human infrastructure; the infrastructure to manage the hygiene of tens of thousands to millions of individual animals. It's not the wet market that's the problem, it's that they don't have any way to clean them.”

A.The outbreak of Covid-19 reveals the problem of city planning

B.Human health is a key factor that city planners take into consideration

C.Some preexisting problems in city planning are the causes of Covid-19

D.People in modern cities can easily keep social distance during pandemics

A.The current measures may also be effective in preventing future diseases

B.The Covid-19 pandemic is a chance for us to help those homeless people

C.Some cities close the roads to bicycles to leave more room for ambulances

D.To some extent, the Covid-19 pandemic changes our view of city planning

A.put off

B.fend off

C.cut off

D.leave off

A.viruses always jump hosts in the process of their development

B.diseases in wild animal population can quickly spread to humans

C.pathogens in wild animals are the major causes for most infectious diseases

D.domesticated animals are mainly responsible for the majority of pandemics

A.good city planning can help minimize the spread of bird flu

B.avian flu usually occurs in places where there is no sewage system

C.we need to prohibit all the wet markets so as to prevent the pandemic

D.it's hard to manage individual animals espeially in urbanizing countries

My past students and collaborators are starting to organize a scientific conference for my 60th birthday to be held about a year from now. Their gesture reminded me of Rabbi Hanina's words:“I have learned much from my teachers, more from my colleagues, and the most from my students.”
We all started as students. Just as kids bump into things as they're learning to maneuver through the world, many of us have scars and bruises from early encounters with our mentors. Conflicts arise when those mentors attempt to establish their authority by trying to make us respect traditional thinking. Memories of these events should encourage us to do better as we change roles and mentor others later in life.
For example, the first advice I received from my postdoctoral mentor was to develop specialized skills and focus them on a narrow niche of the field, where I would establish myself as the world expert. But I decided not to follow this advice as soon as I recognized that by drilling down narrowly, one often encounters the bedrock of a subject, where no further progress can be made. Under these circumstances, the potential for a breakthrough improves with a broader perspective, which identifies the outlands of the bedrock and enables“out of the box” opportunities for drilling deeper around it. This is especially helpful after the discovery of something unusual and unexpected that cannot be explained within the prevailing model.
Keeping in mind the fallacies of indoctrination into a narrow expertise, I encourage my students and postdocs to think broadly and independently about the most exciting problems in astrophysics, such as:“What happened before the big bang?”;“What will happen in our distant cosmic future?”; “What is the nature of dark mater?”;“What happens when one gets close to a black hole singularity?”; “When did life start in the universe?”; or “How can we find relics in space from other technological civilizations?”
It is customary to consider a student's raw potential as a stand-alone commodity whose value can be judged through examinations. But my experience taught me that young scientists do not blossom into exceptional researchers unless they are supported by encouraging words and inspiration; these ingredients are as essential as nutrients and water are for seeds of flowers. Accomplishments are sometimes self-fulfillig prophecies; without the initial belief in the potential of a student to become a successful scientist, this outcome may not come to fruition.
As chair of the Harvard astronomy department for almost a decade, I witnessed multiple examples of students who were initially very slow to make progress but blossomed academically as soon as they selected a different advisor and a new topic for their Ph.D. A successful mentoring experience often reflects a good interaction between a fledgling scientist and an advisor.

A.the aches and pains that one experiences in his life

B.the acts of violence that exist in the process of learning

C.the conflicts that lie between students and their mentors

D.the circumstances when mentors have the authority over their students

A.his mentor was absolutely a narrow-minded person

B.he was professional enough to manage his own study

C.one should use untraditional way to do scientific research

D.one should have a broader perspective so as to drill deeper

A.the lowest point of a building

B.the basic principles of something

C.the solid rock below the loose soil

D.the underlying condition of something

A.indulge in those exciting problems

B.learn the development of the universe

C.develop the capacity of independent thinking

D.have some basic understanding of the big bang

A.water and nutrients

B.encouragement and inspiration

C.good potential and initial belief

D.gradual development and real accomplishment

The ups and downs of life may seem to have no predictable plan. But scientists now know there are very definite life patterns that almost all people share. Today, when we live 20 years longer than our great-grandparents, and when women mysteriously outlive men by seven years, it is clearer than ever that the “game of life” is really a game of trade-offs. As we age, we trade strength for ingenuity, speed for thoroughness, and passion for reason. These exchanges may not always seem fair, but at every age, there are some advantages. So it is reassuring to note that even if you've passed some of your “prime”, you still have other prime years to experience in the future. Certain important primes seem to peak later in time.
WHEN ARE YOU SMARTEST? From 18 to 25, according to IQ scores; but you are more experienced with increasing age. You're sharpest in your 20's; around 30，memory begins to decline, particularly your ability to perform mathematical computations. “But your IQ for other tasks climbs,” says Berkeley psychologist Arthur Jensen. Your vocabulary at age 45, for example, is three times as great as when you graduated from college. At 60, your brain possesses almost four times as much information as it did at age 21. This trade-off between sharpness and wisdom has led psychologist Dr.Leopold Bellak to suggest that “maturity quotients" (MQs instead of IQs) be adopted for adults.
WHEN ARE YOU HEALTHIEST? For men, from 15 to 25; for women 15 to30.
“A man is in his best shape in the decade before age 25,”says New York internist Dr.Donald Tomkins.“His muscles are firmest, his resistance to colds and infection is highest, and his body is most efficient in utilizing nutrients.” Women, for reasons scientists do not understand, get a five-year bonus. Peak health begins to decline when the body process called anabolism (cell growth) is overtaken by the opposite process, catabolism (cell death).“Cells have been dying since bith,” says Tomkins,“but in our late 20's, they start dying faster than they are replaced.”Also, muscle is replaced with fat.
Women also get an additional bonus of good health later in life. The figures of National Institute of Health show that the onset of such “old age” diseases as arthritis, 0.rheumatism and heart ailments denies the generally greater fitness of women: Life expectancy for men is now 68.3; for women 75.9. U.S. aging authority William Kannel says, “Older women with low blood pressure are practically important." However, psychologists believe that by entering the competitive job market in increasing numbers, women may eventually give up their statistical advantage.