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"Time” says the proverb “is money”. This means that every moment well-spent may put some money into our pockets. (1) If our time is usefully employed, it will either turn out some useful and important piece of work which will fetch its price in the market, or it will add to our experience and increase our capacities so as to enable us to earn money when the proper opportunity comes. There can thus be no doubt that time is convertible into money. Let those, who think nothing of wasting time, remember this; let them remember that an hour misspent is equivalent to the loss of a bank-note; and that an hour utilized is tantamount to so much silver or gold; and then they will probably think twice before they give their consent to the loss of any part of their time.Moreover, our life is nothing more than our time. To kill time is therefore a form of suicide. (2) We are shocked when we think of death, and we spare no pains, no trouble, and no expense to preserve life. But we are too often indifferent to the loss of an hour or a day, forgetting that our life is the sum total of the days and of the hours we live. A day or an hour wasted is therefore so much life forfeited. Let us bear this in mind, and waste of time will appear to us in the light of a crime as culpable as suicide itself.There is a third consideration which also tends to warn us against loss of time. Our life is a brief span measuring some sixty or seventy years in all, but nearly one half of this has to be spent in sleep; some years have to be spent over our meals ; some over dressing and undressing ; some in making journeys on land and voyages by sea; some in merry-marking, either on our own account or for the sake of others ; some in celebrating religious and social festivities ; some in watching over the sick-beds of our nearest and dearest relatives. (3) Now if all these years were to be deducted from the term over which our life extends we shall find about fifteen or twenty years at our disposal for active work. Whoever remembers this can never willingly waste a single moment of his life. “It is astonishing" says Lord Chesterfield, “that anyone can squander away in absolute idleness one single moment of that portion of time which is allotted to us in this world. Know the true value of time; snatch, seize, and enjoy every moment of it! ”All time is precious; but the time of our childhood and of our youth is more precious than any other portion of our existence. For those are the periods when alone we can acquire knowledge and develop our faculties and capacities. (4) If we allow these morning hours of life to slip away unutilized, we shall never be able to recoup the loss. As we grow older, our power of acquisition gets blunted, so that the art or science which is not acquired in childhood or youth will never be acquired at all. Just as money laid out at interest doubles and trembles itself in time, so the precious hours of childhood and youth, if properly used, will yield us incalculable advantages. “Every moment you lose,” says Lord Chesterfield, “is so much character and advantage lost; as on the other hand, every moment you now employ usefully is so much time wisely laid out at prodigious interest.”A proper employment of time is of great benefit to us from a moral point of view. Idleness is justly said to be the rust of the mind and an idle brain is said to be Satan's workshop. It is mostly when you do not know what to do with yourself that you do something ill or wrong. The mind of the idler preys upon itself.

Advances in campaign against the Islamic State in Syria and Iraq are forcing the extremists to abandon territory there, generating concerns that they are carving out a new stronghold in oil-rich Libya, Secretary of State John F. Kerry said Tuesday.“As everybody here knows, that country has resources,” Kerry said at a conference of 23 foreign ministers from nations that form the core of a coalition fighting the Islamic State. “The last thing in the world you'd want is a false caliphate with access to billions of dollars in oil revenue. ”In a joint statement, both Kerry and Italian foreign minister Paolo Gentiloni expressed concern over the “growing influence” of Islamic State in Libya. They vowed to “continue to National Accord in its efforts to establish peace and security for the Libyan people.”Kerry ruled out military intervention in Libya by the United States in near future. But he said that could change if there were “some turn of events, like weapons of mass destruction ending up in the hands of the wrong people”.Libya has been in a state of chaos since 2011 when Moammar Gaddafi was ousted. Two rival governments subsequently emerged, and continuing conflict has foiled efforts to establish a united Libyan government.Though the emerging threat in Libya commanded much of the diplomats' attention, the situation in Syria remains troublesome. Success in pushing Islamic State fighters out of an estimated 40 percent of territory they controlled in Iraq and 20 percent to 30 percent of the land they held in Syria has created its own set of urgent problems.Fleeing fighters often booby-trap homes and demolish buildings, which then need to be cleared and rebuilt before residents can return. Kerry urged his fellow foreign ministers to donate more money to a stabilization fund for rebuilding and restoring services in those areas.Now that U. N. -backed Syria peace talks aimed at ending the war have started in Geneva, Kerry called on Russia to stop bombing opposition fighters and the Syrian government to grant humanitarian access to besieged towns.With the onset of peace talks, a cease-fire should follow shortly, he said.“We are at the table, and we expect a cease-fire,” he said. “And we expect adherence to the cease-fire, and we expect full humanitarian access.”In Geneva, where U. N. envoy Staffan de Mistura on Monday declared the official opening of talks between the Syrian government and opposition, both sides said that as far as they were concerned, negotiations had not yet begun.In a statement, the opposition delegation said Syrian rebels are facing “a massive acceleration of Russian and regime military aggression... including attacks on hospitals and critical infrastructurev" near the cities of Aleppo and Homs over the past two days.The Syrian government delegation accused the opposition of acting like “amateurs and not professional politicians”. Syria's United Nations ambassador, Bashar Jaafari, representing Syrian President Basher al-Assad, said his side challenged the participation of two “terrorist” groups in the opposition delegation, according to the state-run Syrian Arab News Agency.The Obama administration is eager for the peace talks to begin and has pressured the opposition to participate. Opposition representatives have said the agreed-upon rules for the negotiations, in a U. N. resolution, call for an end to bombardments and government sieges of civilian areas, as well as the release of prisoners.Russian Foreign Minister Sergei Lavrov told reporters there that his government considered members of Jaish al-Islam and Ahrar al-Sham to be participating in the opposition delegation in their “personal capacity” rather than as official representatives. Lavrov also said that he considers it the responsibility of the United States, as leader of the coalition against the Islamic State in Syria and Iraq, to prevent conflict among the various participants operating strike aircraft over those countries.1.Both Kerry and Paolo Gentiloni agreed upon the following EXCEPT （） .2.Which of the following is INCORRECT according to the passage?3.What did Kerry urge his fellow foreign ministers to do?4.What did the Syrian government delegation accuse the opposition of?

The weight of plastic waste clogging the world’s oceans threatens to exceed all fish by 2050 if the world’s seemingly insatiable appetite for the material continues at the current explosive rate, warned a new report presented on Tuesday.In fact, according to the study by the Ellen MeaArthur Foundation along with the World Economic Forum, “plastics production has surged over the past 50 years, from 15 million tonnes in 1964 to 311 million tonnes in 2014, and is expected to double again over the next 20 years.”The study—The New Plastics Economy: Rethinking The Future of Plastics—introduced at the opening day of the WEF’s annual summit in Davos, Switzerland is the first of its kind to comprehensively assess global plastic packaging flows. The report makes an economic case for what it calls the “New Plastics Economy”, described as “a new approach based on creating effective after-use pathways for plastics; drastically reducing leakage of plastics into natural systems, in particular oceans; and decoupling plastics from fossil feedstocks”.Among the findings, which are based on interviews with over 180 experts and on analysis of over 200 reports, the study estimates that roughly 8 million tonnes of plastics leak into the ocean each year—“which is equivalent to dumping the contents of one garbage truck into ocean every minute”, This amount is expected to double by 2030.“In a business-as-usual scenario, the ocean is expected to contain/tonne of plastic for every 3 tonnes of fish by 2025, and by 2050, more plastics than fish (by weight)” the report continues.What’s more, the report estimates that only 14 percent of plastic packaging is collected for recycling and even less for plastics in general. After sorting, only 5 percent is ultimately retained for subsequent use, which is far below global recycling rates for paper (58 per cent) and iron and steel (70-90 percent).Further, the report examines the carbon impact of plastics production, given that over 90 percent are derived from “virgin fossil feedstocks”. Plastics production represents roughly 6 percent of global oil consumption and “If the current strong growth of plastics usage continues as expected, the plastics sector will account for 20% of total oil consumption and 15% of the global annual carbon budget by 2050.”The report argues that single-use plastics, and plastic packaging specifically, represents a net loss for the economy, as its limited value is outweighed by these negative impacts. It states:After a short first-use cycle, 95% of plastic packaging material value, or USD 80-120 billion annually, is lost to the economy. A staggering 32% of plastic packaging escapes collection systems, generating significant economic costs by reducing urban infrastructure. The cost of such after-use externalities for plastic packaging, plus the cost associated with greenhouse gas emissions from its production, is exceeding the plastic packaging industry’s profit pool.“Linear models of production and consumption are increasingly challenged by the context within which they operate, and this is particularly true for high-volume, low-value materials such as plastic packaging,” said Ellen MacArthur, an accomplished British yachtswoman turned foundation chair.The researchers conclude that in order to get closer to the goal of a “circular economy” —where “consumption happens only in effective bio-cycles; elsewhere use replaces consumption” — both the public and private sector must work towards the goal of creating plastics that can be both recycled and composted.1.Which of the following is CORRECT about New Plastics Economy according to the passage?2.All EXCEPT （） can be found from the findings of The New Plastics Economy.3.Which of the following is INCORRECT according to the passage?4.How to get closer to the goal of circular economy according to the researchers?

“A HARMLESS drudge.” Of the definitions in Samuel Johnson's great English dictionary of 1755, that of “lexicographer”, his own calling, is the most famous, an example of the same wit that led him to define “oats” as “a grain, which in England is generally given to horses, but in Scotland supports the people”.Why name a language column after a harmless drudge? Because Johnson, despite the drudgery, knew that language was not harmless. Its power to inform and to lead astray, to entertain and to annoy, to build co-operation or destroy a reputation, makes language serious stuff, The Economist's “Johnson” column began in 1992 and was later revived online. This week it returns to the print edition, and henceforth will appear fortnightly.Many of the topics tackled are fun: swearing and slang, preferences and peeves. Some are more fundamental. Language reveals a lot about human nature: how people reason differently in a foreign language, or to what extent different languages encode a world view, are some of the most exciting and controversial topics in linguistic research.People care intensely about their language, and so language in the wider world sometimes comes into conflict. The perceived arrogance of Castilians to Catalan threatens to sunder Spain; “language police” in Quebec tell restaurant owners to change “pasta” and “grilled cheese” pates and fromae fondant. At the extreme, the passage of a law downgrading Russian in Ukraine helps spark war in that country ; Vladimir Putin has used it as evidence that Ukrainian nationalists are bent on wiping out Russian culture there. The war has rumbled on since, with language the most obvious symbol of wider identity and sympathy.So the Johnson column treats topics light and heavy as well as language both English and international. A language column is expected to tackle questions of right and wrong. There are roughly two views of how to do this: one top-down, based on authority, prestige, writing and stability; one bottom-up, resting on how most people actually use the language, and open to change.The two schools of thought, known as “prescriptivism”( which sets down how the language should be) and “descriptivism” ( which tells how it is ) , have often been at daggers drawn: English teachers and some usage-book writers on one side, and academic linguists, lexicographers and other usage-book writers on the other. In the caricature, prescriptivists are authoritarians with their heads in the sand, insisting on Victorian-era non-rules. The descriptivists are mocked as “anything-is-correct", embracing every fad, even that Shakespeare should be taught in text-message-speak.An intellectual writing for an elite audience, Samuel Johnson did not shy away from “right” and “wrong”, even “barbarity”, “depravity” and “corruption”, in matters of language. But he declared his task was not to “form” but to “register” (that is, describe) the language; trying to stop change was like trying to “ lash the wind”. Above all, his years of drudging at the dictionary had taught him humility: he knew he was sure to commit “ a few wild blunders, and visible absurdities, from which no work of such multiplicity was ever free”.Prescribing is not really the opposite of describing. Lexicographers from Johnson's day on must describe the language, grounding their definitions in real living English. But that is in order to give stronger roots to a book they know people will use for firm guidance. Academic linguists, the arch-descriptivists, are perfectly willing to call some usages wrong and others plain ugly.1.Which of the following is INCORRECT about Samuel Johnson according to the passage?2.Why is language serious stuff according to the passage?3.From Para 4, the author has listed the conflicts caused by language in the following countries EXCEPT（） .4.Which of the following is NOT MENTIONED in the passage?

Researchers have created male mice with no trace of a Y chromosome, supposedly the defining hallmark of being male.Reproductive biologist Monika Ward of University of Hawaii in Honolulu and colleagues started with mice that have only one X chromosome (and no second sex chromosome). Normally those animals would develop as females. But when the researchers manipulated genes found on the X and another chromosome, the mice became males that could produce immature sperm. Those engineered males fathered offspring with reproductive assistance from the researchers, who injected the immature sperm into eggs, Ward and colleagues report in the Jan. 29 Science.The experiments demonstrate that there are multiple ways to make males, says Richard Behringer, a developmental geneticist at MD Anderson Cancer Center in Houston. “They’ve done it without any Y chromosome gene information,” he says “There’s not even a sniff of the Y around.”At first glance, the experiments would seem to suggest Y chromosomes aren’t necessary for reproduction, which hints that evolution may eventually show Y’s the door. “To me it is a paradigm of the decline and fall of the Y chromosome,” says reproductive biologist Jennifer Marshall Graves of La Trobe University in Melbourne, Australia.But Ward and other researchers say the Y isn’t going anywhere and that interpreting the new results as the chromosome’s death knell is wrong. Because the Y-less males needed help to reproduce, “clearly we need the Y chromosome for full natural male reproduction,” says Mary Ann Handel, a reproductive biologist at the Jackson Laboratory in Bar Harbor, Maine.Ward and colleagues had previously shown that two Y chromosome genes—Sry and Eif2s3y—are crucial for male mouse development. Sry is a master gene that turns on male developmental programming in early embryos. It turns on a gene called Sox9, which then sets off a biochemical chain reaction that leads to male development.But in the new experiments, the researchers turned on Sox9 through other means. Activating Sox9 in a genetically female embryo will cause it to develop as a male, Ward and colleagues found. But those males didn’t make sperm. “The testes were empty,” says Ward.In order to produce sperm, mice need the Eif2s3y gene, the researchers had previously discovered. In the new experiment, the mice were missing the gene because they didn’t have Y chromosomes. So researchers substituted a similar gene from the X chromosome called Eif2s3x. Only one copy of the Y version is needed to make immature, tailless sperm, but it takes at least five copies of the X version to do the same thing. “This indicates that the Y chromosome gene is the strong one,” says Ward.Her research suggests that the Y chromosome has optimized production from genes that are necessary for making males. Making just the right dose of male development factors is how the Y protects itself from evolutionary erasure, Ward says. “Our work does not support that the Y chromosome will disappear.”Graves disagrees, Ward’s work is “a lovely example of how you can lose even a really important gene,” she says. At least two species of rodents have already jettisoned their Y chromosomes entirely. Primates, including humans, don’t have Eif2s3y genes on their Y chromosomes. The new work may help explain how primates get along without the gene, Graves suggests, and the research may “give us useful information about what happens at the end of the Y chromosome.”1.Which of the following is CORRECT according to the passage?2.Why is Eif2s3Y gene crucial for male mouse development?3.Which of the following is INCORRECT according to the passage?4.What can be the best title for this passage?

My last flight to Rome landed at stupid o’clock in the morning so I was almost looking forward to getting a cup of hot coffee from the flight crew. Instead, I opted for holding my eyelids up with two fingers so I could find the first coffee shop in the airport. Coffee always tastes terrible on planes and there could be a simple — and disgusting — reason why.A couple of weeks ago, an assortment of airline employees spilled some of their industry’s secrets in an Ask Reddit thread, and two of them had some unpleasant things to say about the coffee-makers. A user named Muddbutt7 wrote:“Sometimes, the vehicle that fills the potable water for washing hands and making coffee is parked next to the vehicle that in used to dump the [toilets] and fill the blue juice for the lavatories. They’re not supposed to. Sometimes, they parked at a distance from each other, which is policy, yet the guy who is filling the water is using gloves that he hasn’t in over 2 years. ”While a second user named Worseto added:“The coffee is absolutely disgusting because no one washes the container that goes out every morning. The station agents who get paid way too little don’t give a [expletive] about cleaning it. I certainly didn’t when I worked for AA. Also, because we weren’t given the proper supplies to clean it. We pretty much just rinsed it out and dumped coffee into it. ‘‘After reading those sort of stomach-churning confessions, Huffington Post attempted to determine how true those statements are. Abbie Unger, a former flight attendant, told the site:“It is true that the portable water tanks are not cleaned. But they are only filled with potable (drinkable) water, so it’s not like there is old coffee in a big container somewhere. The water doesn’t make for an excellent cup of coffee, but it’s not unsafe.”So basically, the reason that cup of Starbucks during your Delta flight tastes worse than the cup you had at the airport is because of the water, which is a point that has been raised previously. The Environmental Protection Agency began investigating the safety of the water on airplanes in 2004, after discovering that 15%—or 1. 5 out of every 10 planes—tested positive for coliform bacteria in the drinking water.In 2013, NBC 5 looked into whether those numbers had improved and discovered that 12% of planes had at least one positive test for coliform in what was then the EPA’s most recent survey. Although the EPA said that there had not been any cases of anyone getting sick from the water onboard a plane, insiders still say that the tanks—and the hoses that are used to fill them—can be pretty gross (“pretty gross” is a highly scientific term).In a Forbes piece called “Why Airline Crews Skip the Coffee and Tea On Board”, former US Air employee John Goglia wrote:“Thirty years ago when I was working for US Air, we began a process to bleach the water tanks that hold the water and flush out the system. This was done on a regular basis. Yet, it was clear to anyone working on these tanks and their hoses that a lot of sediment was accumulating in the system, sediment that was akin to pond scum. Even after the tanks were bleached and flushed, some sediment always remained.”Of course, there could be other reasons why the coffee tastes so unpleasant. Cornell University scientists believe that the loud, inescapable sound of cabin noise can affect the way we both perceive and taste foods during flight. Either way, we might just stick with coffee served at ground level from now on.1.What attitudes did the author have towards the coffee on planes according to the passage?2.（）is basically the cause of the terrible coffee taste on planes.3.According to the context, what possibly is the Chinese meaning of the word “coliform” in Paragraph 9?4.Which of the following is INCORRECT according to US Air employee John Goglia?

Directions:Write a composition in no less than 150 words on the topic: What do You Think of Advanced Artificial Intelligence? Read the following words in English. You should write according to the outline given below. Write your composition on the ANSWER SHEET.1.Google's DeepMind Alpha Go program has beaten all the world champions of the game Go in a series of battles between man and artificial intelligence.2.Some people fear advanced artificial intelligence because...3.Your attitude towards advanced artificial intelligence

为了寻找实验室试验的替代品，经济学家十分关注历史所提供的自然实验。例如，当中东战争中断了原油运输时，全世界石油价格飞涨。对石油和石油产品的消费者来说，这个事件降低了他们的生活水平。对经济决策者来说，它提出了选择最优反应的难题。但对经济科学家来说，它提供了研究关键自然资源对世界经济影响的机会，而且，在战争引起的石油价格上涨结束后，这种机会还会持续很长时间。因此，在本书中我们要考虑许多历史事件。这些事件之所以具有研究价值，既是因为它们能使我们了解过去的经济，更重要的则是因为它们使我们可以说明并评价现在的经济理论。

Economics is no different. Supply, demand, elasticity, comparative advantage, consumer surplus, deadweight loss—these terms are part of the economist's language. In the coming chapters, you will encounter many new terms and some familiar words that economists use in specialized ways.（1）At first, this new language may seem needlessly arcane. But, as you will see, its value lies in its ability to provide you a new and useful way of thinking about the world in which you live.Economists try to address their subject with a scientist's objectivity. They approach the study of the economy in much the same way as a physicist approaches the study of matter and a biologist approaches the study of life:（2）They devise theories, collect data, and then analyze these data in an attempt to verify or refute their theories.To beginners, it can seem odd to claim that economics is a science. After all, economists do not work with test tubes or telescopes. （3）The essence of science, however, is the scientific methods — the dispassionate development and testing of theories about how the world works.This method of inquiry is as applicable to studying a nation's economy as it is to studying the earth's gravity or a species, evolution. （4）As Albert Einstein once put it, “The whole of science is nothing more than the refinement of everyday thinking.” (225 words).

Of all the people on my holiday shopping list, there was one little boy for whom buying a gift had become increasingly difficult. He's a wonderful child, adorable and loving, and he's not fussy or irritable or spoiled. Though he lives across the country from me, I receive regular updates and photos, and he likes all the things that the boys his age want to play with. Shopping for him should be easy, but I find it hard to summon up any enthusiasm, because in all the years I've given him presents, he never once sent me a thank-you note.“Sending thank-you notes is becoming a lost art,” mourns Mary Mitchell, a syndicated columnist known as “Ms. Demeanor” and author of six etiquette books. In her view, each generation, compared with the one before, is losing a sense of consideration for other people. “Without respect,” she says, “you have conflict.”Ms. Demeanor would be proud of me : I have figured out a way to ensure that my children always send thank-you notes. And such a gesture is important, says Ms. Demeanor, because “a grateful attitude is a tremendous life skill, an efficient and inexpensive way to set ourselves apart in the work force and in our adult lives. Teach your children that the habit of manners comes from inside — it's an attitude based on respecting other people.”A few years ago, as my children descended like piranhas on their presents under the Christmas tree, the only attitude I could see was greed. Where was the appreciation of time and effort?A thank-you note should contain three things: an acknowledgement of the gift (Love the tie with the picture of a horse on it.) ; a recognition of the time and effort spent to select it (You must have shopped all over the state to find such a unique item! ) ; a prediction of how you will use your gift or the way it has enhanced your life (I'll be sure to wear it to the next Mr. Ed convention!).So, five years ago, in one of my rare flashes of parental insight, I decided that the most appropriate time to teach this basic courtesy is while the tinsel is hot. To the horror of my children, I announced that henceforth every gift received will be an occasion for a thank-you note written immediately, on the spot. I have explained to my kids how I have reacted to not hearing from the little boy — how it made me feel unappreciated and unmotivated to repeat the process next year.I have reluctantly given my kids the green light to send e-thank-you notes ; though hand-lettered ones (at least to me) still seem friendlier. But pretty much any thank-you makes the gift giver feel special —just as, we hope, the recipient feels. It's a gesture that perfectly captures the spirit of the holidays.1.The author felt unmotivated when buying a gift for the little boy because he（）.2.According to Ms. Demeanor, showing appreciation has the benefit of （） .3.In a thank-you note, “The book will be my good companion when I am alone.” serves as （） .4.What does the author mean by “while the tinsel is hot”(Line 2, Para. 6)?

From beach balls, pool toys, and jump houses, inflatable technology takes a big step forward for its next frontier: space station. A new kind of tech will be aboard Space X's eighth supply mission to the International Space Station (ISS). A compressed living module will be delivered and attached to the station where, in the void of space, it will expand into a new habitat for astronauts.Designed by Bigelow Aerospace, the inflatable space habitat is one area NASA is exploring for potential deep space habitats and other advanced space missions."The ‘Bigelow Expandable Activity Module', or the BEAM, is an expandable habitat that will be used to investigate technology and understand the potential benefits of such habitats for human missions to deep space,” NASA Administrator Charles Bolden wrote in a blog post. The habitats could be a way to “dramatically increase” the space available for astronauts while also offering added protection from the dangers of space, like radiation and space debris, the NASA press release says.But how is an inflatable space station supposed to be a viable means of housing for space travelers? BEAMs are far more than balloon-like rooms where astronauts can take asylum. Technically, the modules don't inflate — they expand, according to the company. And beyond just air, the habitats are reinforced with an internal metal structure. The outside is composed of multiple layers of material including things like rubber and kevlar to protect form any speeding debris.Inside Space X's Dragon spacecraft on the way to the ISS, the BEAM will be approximately 8 feet in diameter. It will expand once deployed in space to offer 565 cubic feet of space for astronauts. “It'll be the first time human beings will actually step inside this expandable habitat in space,” former astronaut George Zamka, who has worked for Bigelow Aerospace, told USA Today. “There won't be this sense of it being like a balloon.”But astronauts won't be getting inside the module for some time yet. The BEAM will be attached to the Tranquility Node and deployed. Inside the module are a series of tools that will help the crew of the ISS monitor different aspects of the expandable area to see how it acts in space. The crew will watch heat, radiation, orbital debris, and provide information about the viability of using similar modules in the future.The testing is scheduled to go on for a two-year time period, after which the module will be released and burn up in the atmosphere. NASA's partnership with Bigelow fits Mr. Bolden's desire to help grow a robust private sector industry to commercialize aspects of space — a process he sees as vital if humans want to reach farther cosmic destinations. “ The world of low Earth orbit belongs to industry,” Bolden said at a press conference in January 2015.1.What is special about the new living module on Space X's eighth mission to ISS?2.What is the purpose of designing the inflatable space habitat?3.What does the underlined sentence in Paragraph 5 mean?4.Why does NASA intend to commercialize aspects of space?

Asteroids and comets that repeatedly smashed into the early Earth covered the planet’s surface with molten rock during its earliest days, but still may have left oases of water that could have supported the evolution of life, scientists say. The new study reveals that during the planet’s infancy, the surface of the Earth was a hellish environment, but perhaps not as hellish as often thought, scientists added.Earth formed about 4.5 billion years ago. The first 500 million years of its life are known as the Hadean Eon. Although this time amounts to more than 10 percent of Earth’s history, little is known about it, since few rocks are known that are older than 3.8 billion years old.For much of the Hadean, Earth and its sister worlds in the inner solar system were pummeled with an extraordinary number of cosmic impacts. “It was thought that because of these asteroids and comets flying around colliding with Earth, conditions on early Earth may have been hellish,” said lead study author Simone Marchi, a planetary scientist at the Southwest Research Institute in Boulder, Colorado. This imagined hellishness gave the eon its name—Hadean comes from Hades, the lord of the underworld in Greek mythology.However, in the past dozen years or so, a radically different picture of the Hadean began to emerge. Analysis of minerals trapped within microscopic zircon crystals dating from this eon “suggested that there was liquid water on the surface of the Earth back then, clashing with the previous picture that the Hadean was hellish,” Marchi said. This could explain why the evidence of the earliest life on Earth appears during the Hadean—maybe the planet was less inhospitable during that eon than previously thought.The exact timing and magnitude of the impacts that smashed Earth during the Hadean are unknown. To get an idea of the effects of this bombardment, Machi and his colleagues looked at the moon, whose heavily cratered surface helped model the battering that its close neighbor Earth must have experienced back then.“We also looked at highly siderophile elements (elements that bind tightly to iron), such as gold, delivered to Earth as a result of these early collisions, and the amounts of these elements tells us the total mass accreted by Earth as the results of these collisions,” Marchi said. Prior research suggests these impacts probably contributed less than 0.5 percent of the Earth’s present-day mass.The researchers discovered that “the surface of the Earth during the Hadean was heavily affected by very large collisions, by impactors larger than 100 kilometers or so — really, really big impactors,” Marchi said. “When Earth has a collision with an object that big, that melts a large volume of the Earth’s crust and mantle, covering a large fraction of the surface,” Marchi added. These findings suggest that Earth’s surface was buried over and over again by large volumes of molten rock — enough to cover the surface of the Earth several times. This helps explain why so few rocks survive from the Hadean, the researchers said.1.Why is it little known about the Earth's first 500 million years?2.Why is the early Earth imagined to be hellish?3.Why was the early Earth in fact less inhospitable than often thought?4.How can the moon help with the understanding of the impacts that smashed the Earth?

Unfortunately, after completing the second volume, Manchester's health declined and the rest of the project stalled. So great was public interest in the long-delayed final volume that it was the subject of a front page story in The New York Times.Eventually, in 2003, Manchester asked his friend Paul Reid to complete the trilogy. Now, nearly a decade later, Reid has published The Last Lion, the final piece of this monumental undertaking. Reid starts when Churchill was appointed prime minister in May 1940 and follows him through his death in 1965. While most of this volume is appropriately devoted to World War II, it also includes the vast expansion of the British welfare state following the war, the start of the Cold War and the enormous dangers it carried, and the loss of the British Empire.Reid has written a thorough and complete analysis of these years, and it is a worthy finale to the first two volumes. Exhaustively researched and carefully written, it draws on a full range of primary and secondary materials. This book will be essential reading for those who enjoyed the first two volumes and those with a deep interest in understanding this seminal figure and his place in history.Reid does a wonderful job of capturing Churchill in all his complexity. He gives Churchill great praise for his personal courage and inspirational leadership during the dark days when Britain stood alone, but he is equally clear about Churchill's poor strategic judgments, such as the efforts to defend Greece and Crete, the Allied assault on Anzio, and the decision to send the battleship Prince of Wales and Winston Churchill was one of the central statesmen of the 20th century and, almost 50 years after his death, remains a subject of enduring fascination. Part of the current interest in this venerable figure can be attributed to two superb biographies written in the 1980s by historian William Manchester: The Last Lion: Visions of Glory and The Last Lion: Alone. These two books examined the first two-thirds of Churchill's life.battle cruiser Repulse to the South China Sea without adequate air cover where they were promptly sunk by the Japanese.He highlights Churchill's naivete in dealing with Soviet Premier Stalin in the early years of the war, but praises his prescience in anticipating Stalin's land grab in Eastern Europe at the end of the conflict.Reid also gives welcome attention to aspects of the war — such as Churchill's fear that the United States might decide to put its primary emphasis on defeating Japan regardless of the “Germany first” understanding he shared with Roosevelt that have received little attention in other books.1.What can be known about the two biographies of Churchill?2.Why did the biography once become a front page story in the New York Times?3.Why does the third volume prove to be worthy?4.What can we know about Churchill through the third volume?

Mr Gordon is right that the second industrial revolution involved never-to-be-repeated changes. But that does not mean that driverless cars count for nothing. Messrs Erixon and Weigel are also right to worry about the West's dismal recent record in producing new companies. But many old firms are not run by bureaucrats and have reinvented themselves many times over: General Electric must be on at least its ninth life. And the impact of giant new firms born in the past 20 years such as Uber, Google and Facebook should not be underestimated: they have all the Schumpeterian characteristics the authors admire.On the pessimists' side the strongest argument relies not on closely watching corporate and investor behavior but rather on macro-level statistics on productivity. The figures from recent years are truly dismal. Karim Foda, of the Brookings Institution, calculates that labor productivity in the rich world is growing at its slowest rate since 1950. Total factor productivity (which tries to measure innovation) has grown at just 0.1% in advanced economies since 2004, well below its historical average.Optimists have two retorts. The first is that there must be something wrong with the figures. One possibility is that they fail to count the huge consumer surplus given away free of charge on the Internet. But this is unconvincing. The official figures may well be understating the impact of the Internet revolution, just as they downplayed the impact of electricity and cars in the past, but they are not understating it enough to explain the recent decline in productivity growth.Another, second line of argument that the productivity revolution has only just begun is more persuasive. Over the past decade many IT companies may have focused on things that were more “fun than fundamental” in Paul Krugman's phrase. But Silicon Valley's best companies are certainly focusing on things that change the material world.Uber and Airbnb are bringing dramatic improvements to two large industries that have been more or less stuck for decades. Morgan Stanley estimates that driverless cars could result in $ 507 billion a year of productivity gains in America, mainly from people being able to stare at their laptops instead of at the road.1.What has led to the pessimistic opinion concerning the world's economy?2.The first argument on the optimists' side is unconvincing because the official figures（）.3.What is true about the IT companies in Silicon Valley?4.How can driverless cars benefit American industries?

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