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2018年6月英语六级阅读真题及答案 第2套






Did Sarah Josepha Hale write "Mary's Little Lamb," the eternal nursery rhyme (儿歌) about a girl named Mary with a stubborn lamb? This is still disputed, but it's clear that the woman __26__ for writing it was one of America's most fascinating __27__. In honor of the poem's publication on May 24, 1830, here's more about the __28__ author's life.

Hale wasn't just a writer, she was also a __29__ social advocate, and she was particularly __30__ with an ideal New England, which she associated with abundant Thanksgiving meals that she claimed had "a deep moral influence." She began a nationwide __31__ to have a national holiday declared that would bring families together while celebrating the __32__ festivals. In 1863, after 17 years of advocacy including letters to five presidents, Hale got it. President Abraham Lincoln, during the Civil War, issued __33__ setting aside the last Thursday in November for the holiday.

The true authorship of "Mary's Little Lamb" is disputed. According to the New England Historical Society, Hale wrote only part of the poem, but claimed authorship. Regardless of the author, it seems that the poem was __34__ by a real event. When young Mary Sawyer was followed to school by a lamb in 1816, it caused some problems. A bystander named John Roulstone wrote a poem about the event, then, at some point, Hale herself seems to have helped write it. However, if a 1916 piece by her great-niece is to be trusted, Hale claimed for the __35__ of her life that "some other people pretended that someone else wrote the poem".



























Grow Plants Without Water

[A]Ever since humanity began to farm our ownfood, we've faced the unpredictable rain that isboth friend and enemy. It comes and goes withoutmuch warning, and a field of lush (茂盛的) leafygreens one year can dry up and blow away the next. Food security and fortunes depend on sufficientrain, and nowhere more so than in Africa, where 96% of farmland depends on rain instead ofthe irrigation common in more developed places. It has consequences: South Africa's ongoingdrought-the worst in three decades-will cost at least a quarter of its corn crop this year.

[B]Biologist Jill Farrant of the University of Cape Town in South Africa says that nature hasplenty of answers for people who want to grow crops in places with unpredictable rainfall. Sheis hard at work finding a way to take traits from rare wild plants that adapt to extreme dryweather and use them in food crops. As the earth's climate changes and rainfall becomes evenless predictable in some places, those answers will grow even more valuable. "The type offarming I'm aiming for is literally so that people can survive as it's going to get more and moredry," Farrant says.

[C]Extreme conditions produce extremely tough plants. In the rusty red deserts of SouthAfrica, steep-sided rocky hills called inselbergs rear up from the plains like the bones of theearth. The hills are remnants of an earlier geological era, scraped bare of most soil and exposedto the elements. Yet on these and similar formations in deserts around the world, a few fierceplants have adapted to endure under ever-changing conditions.

[D]Farrant calls them resurrection plants (复苏植物). During months without water under aharsh sun, they wither, shrink and contract until they look like a pile of dead gray leaves. Butrainfall can revive them in a matter of hours. Her time-lapse (间歇性拍摄的) videos of therevivals look like someone playing a tape of the plant's death in reverse.

[E]The big difference between "drought-tolerant" plants and these tough plants: metabolism. Many different kinds of plants have developed tactics to weather dry spells. Some plants storereserves of water to see them through a drought; others send roots deep down to subsurfacewater supplies. But once these plants use up their stored reserve or tap out the undergroundsupply, they cease growing and start to die. They may be able to handle a drought of somelength, and many people use the term "drought tolerant" to describe such plants, but theynever actually stop needing to consume water, so Farrant prefers to call them droughtresistant.

[F]Resurrection plants, defined as those capable of recovering from holding less than 0.1 grams of water per gram of dry mass, are different. They lack water-storing structures, andtheir existence on rock faces prevents them from tapping groundwater, so they have insteaddeveloped the ability to change their metabolism. When they detect an extended dry period, they divert their metabolisms, producing sugars and certain stress-associated proteins andother materials in their tissues. As the plant dries, these resources take on first the propertiesof honey, then rubber, and finally enter a glass-like state that is "the most stable state thatthe plant can maintain," Farrant says. That slows the plant's metabolism and protects its dried-out tissues. The plants also change shape, shrinking to minimize the surface area throughwhich their remaining water might evaporate. They can recover from months and years withoutwater, depending on the species.

[G]What else can do this dry-out-and-revive trick? Seeds-almost all of them. At the start ofher career, Farrant studied "recalcitrant seeds (顽拗性种子)," such as avocados, coffee andlychee. While tasty, such seeds are delicate-they cannot bud and grow if they dry out (as youmay know if you've ever tried to grow a tree from an avocado pit). In the seed world, thatmakes them rare, because most seeds from flowering plants are quite robust. Most seeds canwait out the dry, unwelcoming seasons until conditions are right and they sprout (发芽). Yetonce they start growing, such plants seem not to retain the ability to hit the pause button onmetabolism in their stems or leaves.

[H]After completing her Ph. D. on seeds, Farrant began investigating whether it might bepossible to isolate the properties that make most seeds so resilient (迅速恢复活力的) andtransfer them to other plant tissues. What Farrant and others have found over the past twodecades is that there are many genes involved in resurrection plants' response to dryness. Many of them are .the same that regulate how seeds become dryness-tolerant while stillattached to their parent plants. Now they are trying to figure out what molecular signalingprocesses activate those seed-building genes in resurrection plants-and how to reproducethem in crops. "Most genes are regulated by a master set of genes," Farrant says, "We'relooking at gene promoters and what would be their master switch."

[I]Once Farrant and her colleagues feel they have a better sense of which switches to throw, they will have to find the best-way to do so in useful crops. "I'm trying three methods ofbreeding," Farrant says: conventional, genetic modification and gene editing. She says sheis aware that plenty of people do not want to eat genetically modified crops, but she ispushing ahead with every available tool until one works. Farmers and consumers alike canchoose whether or not to use whichever version prevails: "I'm giving people an option."

[J]Farrant and others in the resurrection business got together last year to discuss the bestspecies of resurrection plant to use as a lab model. Just like medical researchers use rats totest ideas for human medical treatments, botanists use plants that are relatively easy to grow ina lab or greenhouse setting to test their ideas for related species. The Queensland rockviolet is one of the best studied resurrection plants so far, with a draft genome (基因图谱) published last year by a Chinese team. Also last year, Farrant and colleagues published adetailed molecular study of another candidate, Xerophyta viscosa, a tough-as-nail SouthAfrican plant with lily-like flowers, and she says that a genome is on the way. One or both ofthese models will help researchers test their ideas-so far mostly done in the lab-on test plots.

[K]Understanding the basic science first is key. There are good reasons why crop plants do notuse dryness defenses already. For instance, there's a high energy cost in switching from aregular metabolism to an almost-no-water metabolism. It will also be necessary to understandwhat sort of yield farmers might expect and to establish the plant's safety. "The yield is nevergoing to be high," Farrant says, so these plants will be targeted not at Iowa farmers trying tosqueeze more cash out of high-yield fields, but subsistence farmers who need help to survivea drought like the present one in South Africa. "My vision is for the subsistence farmer," Farrant says. "I'm targeting crops that are of African value."

36. There are a couple of plants tough and adaptable enough to survive on bare rocky hillsand in deserts.

37. Farrant is trying to isolate genes in resurrection plants and reproduce them in crops.

38. Farmers in South Africa are more at the mercy of nature, especially inconsistent rainfall.

39. Resurrection crops are most likely to be the choice of subsistence farmers.

40. Even though many plants have developed various tactics to cope with dry weather, theycannot survive a prolonged drought.

41. Despite consumer resistance, researchers are pushing ahead with genetic modification ofcrops.

42. Most seeds can pull through dry spells and begin growing when conditions are ripe, butonce this process starts, it cannot be held back.

43. Farrant is working hard to cultivate food crops that can survive extreme dryness bystudying the traits of rare wild plants.

44. By adjusting their metabolism, resurrection plants can recover from an extended period ofdrought.

45. Resurrection plants can come back to life in a short time after a rainfall.36.C











Passage One

Questions 46 to 50 are based on the followingpassage.

Human memory is notoriously unreliable. Evenpeople with the sharpest facial-recognition skills canonly remember so much.

It's tough to quantify how good a person is at remembering. No one really knows how manydifferent faces someone can recall, for example, but various estimates tend to hover in thethousands—based on the number of acquaintances a person might have.

Machines aren't limited this way. Give the right computer a massive database of faces, and itcan process what it sees—then recognize a face it's told to find—with remarkable speed andprecision. This skill is what supports the enormous promise of facial-recognition software inthe 21st century. It's also what makes contemporary surveillance systems so scary.

The thing is, machines still have limitations when it comes to facial recognition. And scientistsare only just beginning to understand what those constraints are. To begin to figure out howcomputers are struggling, researchers at the University of Washington created a massivedatabase of faces—they call it MegaFace—and tested a variety of facial-recognition algorithms (算法) as they scaled up in complexity. The idea was to test the machines on a database thatincluded up to 1 million different images of nearly 700,000 different people—and not just a largedatabase featuring a relatively small number of different faces, more consistent with what'sbeen used in other research.

As the databases grew, machine accuracy dipped across the board. Algorithms that were right 95% of the time when they were dealing with a 13,000-image database, for example, wereaccurate about 70% of the time when confronted with 1 million images. That's still prettygood, says one of the researchers, Ira Kemelmacher-Shlizerman. "Much better than weexpected," she said.

Machines also had difficulty adjusting for people who look a lot alike—either doppelgangers (长相极相似的人), whom the machine would have trouble identifying as two separate people, or thesame person who appeared in different photos at different ages or in different lighting, whomthe machine would incorrectly view as separate people.

"Once we scale up, algorithms must be sensitive to tiny changes in identities and at the sametime invariant to lighting, pose, age," Kemelmacher-Shlizerman said.

The trouble is, for many of the researchers who'd like to design systems to address thesechallenges, massive datasets for experimentation just don't exist—at least, not in formatsthat are accessible to academic researchers. Training sets like the ones Google and Facebookhave are private. There are no public databases that contain millions of faces. MegaFace'screators say it's the largest publicly available facial-recognition dataset out there.

"An ultimate face recognition algorithm should perform with billions of people in a dataset," the researchers wrote.

46. Compared with human memory, machines can ________.

A) identify human faces more efficiently

B) tell a friend from a mere acquaintance

C) store an unlimited number of human faces

D) perceive images invisible to the human eye

47. Why did researchers create MegaFace?

A) To enlarge the volume of the facial-recognition database.

B) To increase the variety of facial-recognition software.

C) To understand computers' problems with facial recognition.

D) To reduce the complexity of facial-recognition algorithms.

48. What does the passage say about machine accuracy?

A) It falls short of researchers' expectations.

B) It improves with added computing power.

C) It varies greatly with different algorithms.

D) It decreases as the database size increases.

49. What is said to be a shortcoming-of facial-recognition machines?

A) They cannot easily tell apart people with near-identical appearances.

B) They have difficulty identifying changes in facial expressions.

C) They are not sensitive to minute changes in people's mood.

D) They have problems distinguishing people of the same age.

50. What is the difficulty confronting researchers of facial-recognition machines?

A) No computer is yet able to handle huge datasets of human faces.

B) There do not exist public databases with sufficient face samples.

C) There are no appropriate algorithms to process the face samples.

D) They have trouble converting face datasets into the right format.

Passage Two

Questions 51 to 55 are based on the following passage.

There're currently 21.5 million students in America, and many will be funding their college on borrowed money. Given that there's now over $1.3 trillion in student loans on the books, it's pretty clear that many students are far from sensible. The average student's debt upon graduation now approaches $40,000, and as college becomes ever more expensive, calls to make it "free" are multiplying. Even Hillary Clinton says that when it comes to college, "Costs won't be a barrier."

But the only way college could be free is if the faculty and staff donated their time, the buildings required no maintenance, and campuses required no utilities. As long as it's impossible to produce something from nothing, costs are absolutely a barrier.

The actual question we debate is who should pay for people to go to college. If taxpayers are to bear the cost of forgiving student loans, shouldn't they have a say in how their money is used?

At least taxpayers should be able to decide what students will study on the public dime. If we're going to force taxpayers to foot the bill for college degrees, students should only study those subjects that're of greatest benefit to taxpayers. After all, students making their own choices in this respect is what caused the problem in the first place. We simply don't need more poetry, gender studies, or sociology majors. How do we know which subjects benefit society? Easy.

Average starting salaries give a clear indication of what type of training society needs its new workers to have. Certainly, there're benefits to a college major beyond the job a student can perform. But if we're talking about the benefits to society, the only thing that matters is what the major enables the student to produce for society. And the value of what the student can produce is reflected in the wage employers are willing to pay the student to produce it.

A low wage for elementary school teachers, however, doesn't mean elementary education isn't important. It simply means there're too many elementary school teachers already.

Meanwhile, there're few who're willing and able to perform jobs requiring a petroleum engineering major, so the value of one more of those people is very high.

So we can have taxpayers pick up students' tuition in exchange for dictating what those students will study. Or we can allow students both to choose their majors and pay for their education themselves. But in the end, one of two things is true:

Either a college major is worth its cost or it isn't. If yes, taxpayer financing isn't needed. If not, taxpayer financing isn't desirable. Either way, taxpayers have no business paying for students' college education.

51. What does the author think of college students funding their education through loans?

A) They only expect to get huge returns.

B) They are acting in an irrational way.

C) They benefit at taxpayers' expense.

D) They will regret doing so someday.

52. In the author's opinion, free college education is ________.

A) impractical

B) unsustainable

C) a goal to strive for

D) a way to social equality

53. What should students do if taxpayers are to bear their college costs?

A) Work even harder to repay society.

B) Choose their subjects more carefully.

C) Choose majors that will serve society's practical needs.

D) Allow taxpayers to participate in college administration.

54. What does the author say about the value of a student's college education?

A) It is underestimated by profit-seeking employers.

B) It is to be proved by what they can do on the job.

C) It is well reflected in their average starting salary.

D) It is embodied in how they remove social barriers.

55. What message does the author want to convey in the passage?

A) Students should think carefully whether to go to college.

B) Taxpayers should only finance the most gifted students.

C) The worth of a college education is open to debate.

D) College students should fund their own education.

Passage one






Passage two







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