2019年高考英语真题分类汇编专题09：说明文类阅读理解

    By the end of the century, if not sooner, the world's oceans will be bluer and greener thanks to a warming climate, according to a new study.

    At the heart of the phenomenon lie tiny marine microorganisms (海洋微生物) called phytoplankton. Because of the way light reflects off the organisms, these phytoplankton create colourful patterns at the ocean surface. Ocean colour varies from green to blue, depending on the type and concentration of phytoplankton. Climate change will fuel the growth of phytoplankton in some areas, while reducing it in other spots, leading to changes in the ocean's appearance.

    Phytoplankton live at the ocean surface, where they pull carbon dioxide (二氧化碳) into the ocean while giving off oxygen. When these organisms die, they bury carbon in the deep ocean, an important process that helps to regulate the global climate. But phytoplankton are vulnerable to the ocean's warming trend. Warming changes key characteristics of the ocean and can affect phytoplankton growth, since they need not only sunlight and carbon dioxide to grow, but also nutrients.

    Stephanie Dutkiewicz, a scientist in MIT's Center for Global Change Science, built a climate model that projects changes to the oceans throughout the century. In a world that warms up by 3℃, it found that multiple changes to the colour of the oceans would occur. The model projects that currently blue areas with little phytoplankton could become even bluer. But in some waters, such as those of the Arctic, a warming will make conditions riper for phytoplankton, and these areas will turn greener. "Not only are the quantities of phytoplankton in the ocean changing." she said, "but the type of phytoplankton is changing."

    Want to explore new cultures, meet new people and do something worthwhile at the same time? You can do all the three with Global Development Association (GDA).Whatever stage of life you're at, wherever you go and whatever project you do in GDA, you'll create positive changes in a poor and remote community (社区).

    We work with volunteers of all ages and backgrounds. Most of our volunteers are aged 17-24. Now we need volunteer managers aged 25-75.They are extremely important in the safe and effective running of our programmes. We have such roles as project managers, mountain leaders, and communication officers.

    Depending on which role you choose, you could help to increase a community's access to safe drinking water, or help to protect valuable local cultures. You might also design an adventure challenge to train young volunteers.

    Not only will you help our young volunteers to develop personally, you'll also learn new skills and increase your cultural awareness. You may have chances to meet new people who'll become your lifelong friends.

    This summer we have both 4-week and 7-week programmes:

    GDA ensures that volunteers work with community members and local project partners where our help is needed. All our projects aim to promote the development of poor and remote communities.

    There is no other chance like a GDA programme. Join us as a volunteer manager to develop your own skills while bringing benefits to the communities.

    Find out more about joining a GDA programme:

    Website: www.glodeve.org

    Email: humanresources@glodeve.org

    How does an ecosystem（生态系统）work? What makes the populations of different species the way they are? Why are there so many flies and so few wolves? To find an answer, scientists have built mathematical models of food webs, noting who eats whom and how much each one eats.

    With such models, scientists have found out some key principles operating in food webs. Most food webs, for instance, consist of many weak links rather than a few strong ones. When a predator（掠食动物）always eats huge numbers of a single prey（猎物）, the two species are strongly linked; when a predator lives on various species, they are weakly linked. Food webs may be dominated by many weak links because that arrangement is more stable over the long term. If a predator can eat several species, it can survive the extinction（灭绝）of one of them. And if a predator can move on to another species that is easier to find when a prey species becomes rare, the switch allows the original prey to recover. The weak links may thus keep species from driving one another to extinction.

Mathematical models have also revealed that food webs may be unstable, where small changes of top predators can lead to big effects throughout entire ecosystems. In the 1960s, scientists proposed that predators at the top of a food web had a surprising amount of control over the size of populations of other species—including species they did not directly attack.

    And unplanned human activities have proved the idea of top-down control by top predators to be true. In the ocean, we fished for top predators such as cod on an industrial scale, while on land, we killed off large predators such as wolves. These actions have greatly affected the ecological balance.

    Scientists have built an early-warning system based on mathematical models. Ideally, the system would tell us when to adapt human activities that are pushing an ecosystem toward a breakdown or would even allow us to pull an ecosystem back from the borderline. Prevention is key, scientists says because once ecosystems pass their tipping point（临界点）, it is remarkably difficult for them to return.

History Fair Competition

    Understanding history is vital to understanding ourselves as a people and as a nation.

    History is much more than the study of dusty old objects and events long past. It is an essential part of who we are today and who we will become. Thornton fiddle School History Fair Competition makes understanding history exciting, engaging, and fun！

    This Year's Theme

    All participants must address how communication or transportation technology has promoted the quality of life for Americans throughout history. To many people, technology means computers, hand-held devices, or vehicles that travel to distant planets. However, technology is also the application of scientific knowledge to solve a problem, touching lives in countless ways.

    Individuals or groups may enter one of the following categories:

    Performance

    Documentary（纪实作品）

    Essay Writing

    Category Requirements

    Performance: A dramatic presentation of the topic no more than 10 minutes long. If special clothes are used, they should truly represent a given period.

    Documentary: A visual presentation（such as a video, slide show, or computer project）no more than 10 minutes long. A desktop computer, screen, projector, and loudspeakers will be available. Students must provide their presentations on CDs before Friday, March 23.

    Essay Writing: An academic paper of 2, 000 to 2, 500 words. No illustrations（图解）are allowed. Please do not include covers. A list of references must be included.

    Important Dates

    January 5      Submit a topic proposal to your history teacher. The teacher may require a second proposal if the first is off-topic or unclear.

    February 5      Submit a first draft of your essay, performance script（剧本）, or documentary highlights.

    February 19    A committee of teachers will evaluate materials and give opinions. Students then have an opportunity to improve their products.

    March 9          Submit a final draft of your essay.

    March 15          Performance and documentary committee preview

    March 24          Thornton Middle School History Fair Competition

    7:00A. M-9:00A. M          Participants signing in at the gym

    10:00A. M. -6:00PM.        Competition and judges' review

    7:00P.M.                   Awards ceremony and picnic

    Monkeys seem to have a way with numbers.

    A team of researchers trained three Rhesus monkeys to associate 26 clearly different symbols consisting of numbers and selective letters with 0-25 drops of water or juice as a reward. The researchers then tested how the monkeys combined—or added—the symbols to get the reward.

    Here's how Harvard Medical School scientist Margaret Livingstone, who led the team, described the experiment: In their cages the monkeys were provided with touch screens. On one part of the screen, a symbol would appear, and on the other side two symbols inside a circle were shown. For example, the number 7 would flash on one side of the screen and the other end would have 9 and 8. If the monkeys touched the left side of the screen they would be rewarded with seven drops of water or juice; if they went for the circle, they would be rewarded with the sum of the numbers—17 in this example.

    After running hundreds of tests, the researchers noted that the monkeys would go for the higher values more than half the time, indicating that they were performing a calculation, not just memorizing the value of each combination.

    When the team examined the results of the experiment more closely, they noticed that the monkeys tended to underestimate（低估）a sum compared with a single symbol when the two were close in value—sometimes choosing, for example, a 13 over the sum of 8 and 6. The underestimation was systematic: When adding two numbers, the monkeys always paid attention to the larger of the two, and then added only a fraction（小部分）of the smaller number to it.

    "This indicates that there is a certain way quantity is represented in their brains, "Dr. Livingstone says. "But in this experiment what they're doing is paying more attention to the big number than the little one.”

    Before the 1830s, most newspapers were sold through annual subscriptions in America, usually $8 to $10 a year. Today $8 or $10 seems a small amount of money, but at that time these amounts were forbidding to most citizens. Accordingly, newspapers were read almost only by rich people in politics or the trades. In addition, most newspapers had little in them that would appeal to a mass audience. They were dull and visually forbidding. But the revolution that was taking place in the 1830s would change all that.

    The trend, then, was toward the "penny paper"-a term referring to papers made widely available to the public. It meant any inexpensive newspaper; perhaps more importantly it meant newspapers that could be bought in single copies on the street.

    This development did not take place overnight. It had been possible(but not easy)to buy single copies of newspapers before 1830,but this usually meant the reader had to go down to the printer's office to purchase a copy. Street sales were almost unknown. However, within a few years, street sales of newspapers would be commonplace in eastern cities. At first the price of single copies was seldom a penny-usually two or three cents was charged-and some of the older well-known papers charged five or six cents. But the phrase "penny paper" caught the public's fancy, and soon there would be papers that did indeed sell for only a penny.

    This new trend of newspapers for "the man on the street" did not begin well. Some of the early ventures(企业)were immediate failures. Publishers already in business, people who were owners of successful papers, had little desire to change the tradition. It took a few youthful and daring businessmen to get the ball rolling.

    As data and identity theft becomes more and more common, the market is growing for biometric(生物测量)technologies—like fingerprint scans—to keep others out of private e-spaces. At present, these technologies are still expensive, though.

    Researchers from Georgia Tech say that they have come up with a low-cost device(装置)that gets around this problem: a smart keyboard. This smart keyboard precisely measures the cadence(节奏)with which one types and the pressure fingers apply to each key. The keyboard could offer a strong layer of security by analyzing things like the force of a user's typing and the time between key presses. These patterns are unique to each person. Thus, the keyboard can determine people's identities, and by extension, whether they should be given access to the computer it's connected to—regardless of whether someone gets the password right.

    It also doesn't require a new type of technology that people aren't already familiar with. Everybody uses a keyboard and everybody types differently.

    In a study describing the technology, the researchers had 100 volunteers type the word "touch" four times using the smart keyboard. Data collected from the device could be used to recognize different participants based on how they typed, with very low error rates. The researchers say that the keyboard should be pretty straightforward to commercialize and is mostly made of inexpensive, plastic-like parts. The team hopes to make it to market in the near future.