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A new study shows that the three biggest frog groups—the hyloidea, microhylidae and the natatanura—all trace their origins to an expansion that occurred after 66 million years ago. This impressive diversification of species appears to have occurred on the heels of the asteroid, which struck what is now the edge of the Yucatan Peninsula in Mexico.The scientists sampled a core set of 95 genes from the DNA of 156 frog species. They then combined this data with genetic information from an additional 145 species to produce a detailed “family tree” of frogs, based on their genetic relationships.“Nobody had seen this result before,” said co-author Peng Zhang, from Sun Yat-Sen University in Guangzhou, China. “We re-did the analysis using different parameter settings, but the result remained the same. I realized the signal was very strong in our data. What I saw could not be a false thing.”Another author, David Blackburn, from the Florida Museum of Natural History, explained: “Frogs have been around for well over 200 million years, but this study shows it wasn’t until the extinction of the dinosaurs that we had this burst of frog diversity that resulted in the vast majority of frogs we see today.” Dr. Blackburn said the speed at which frogs diversified after the impact suggests that the survivors were probably filling up new ecological niches.The Chicxulub event would have destroyed a large proportion of the vegetation on Earth. But as forests began to recover after the event, frogs seem to have been one of the groups that made the most of the new habitats. The researchers point out that none of the frog lineages that originate before the extinction and survive through the asteroid impact happen to be adapted to living in trees.The study also indicates that global frog distribution tracks the break-up of the supercontinents beginning with Pangaea about 200 million years ago and then Gondwana, which split into South America and Africa. Frogs likely used Antarctica, not yet encased in ice sheets, as a stepping stone from South America to Australia.“I think the most exciting thing about our study is that we show that frogs are such a strong animal group. They survived... the mass extinction that completely erased dinosaurs, said Peng Zhang. However, frogs—like other amphibians—face many challenges today, including habitat loss due to logging and diseases such as the chytrid fungus and ranavirus.54. The underlined phrase “on the heels of” in Paragraph 1 most probably means （）.55. Peng Zhang’s remarks show that （）.56. According to Paragraph 4, frogs diversified probably because （）.57. What is the main idea of Paragraph 5?58. What can be inferred from Paragraph 6?59. The author’s attitude towards frogs’ future is （）.

In August of 2001, Mitch Prinstein, a psychology professor who had just been hired at Yale University, offered his first class at the school: a course he had developed about popularity among children and adolescents. By the time the enrollment for the course was official, 550 students—a tenth of the school’s undergraduate population—had signed up to learn about that thing that is, variously, an aspiration and a scourge and a mystery: popularity. The course was popular among undergrads because they had seen popularity affecting people’s ability to find success and fulfilling friendships.There is more than one way to be popular. Prinstein, now a professor at the University of North Carolina, breaks down his own treatment of popularity across two broad dimensions: status—the kind of popularity we tend to associate with high school, the stuff of being known and admired though not necessarily liked—and interpersonal likability. Likability is related to charm, to friendliness, to inquisitiveness—it’s the charisma that draws other people to you, largely independent of status or beauty or any of the other metrics that generally give people rank in American culture.But then there is status: the kind of popularity that operates according to hierarchies. The kind that confers admiration but not necessarily true esteem. The kind most commonly associated with high school. Status, too, Prinstein argues, can affect people's brains and their bodies overall—in adolescence, and far beyond.What happens in the teenage years, Prinstein suggests, is a kind of perfect storm, neurologically speaking: At the start of puberty, the brain grows more dramatically than at any other point in one’s life. Myelin, the fatty substance that coats the neurons and allows the brain to function efficiently, increases, affording a burst of neural activity. Those shifts, along with others, aid the brain’s adolescent transition from childish ways of thought (impulsive, relatively un-self-conscious) to adulthood’s more logical, ruminative, and other-oriented modes.The result: Newfound brain capacity collides with newfound self-consciousness. The adolescent brain is primed both to take in the world around it more than ever before, and to process that information with more self-awareness than ever before. Which is another way of saying that teenagers are particularly cognizant of identity—and another way, too, of explaining why, as Jennifer Senior put it in New York Magazine, “most American high schools are almost sadistically unhealthy places to send adolescents.” It’s a powder keg, emotionally, and popularity—or, more specifically, teens conception of popularity—is a fuse.48. What can be learned from Paragraph 1?49. Professor Prinstein’s study of popularity shows that （）.50. The bold-faced word “charisma” in Paragraph 2 means （）.51. Status differs from interpersonal likability in that status （）.52. Growth of the brain during adolescence makes teenagers （）.53. According to the last paragraph, American high schools are unhealthy places because （）.

There is ambition and there is Silicon Valley ambition. For where else on a map could a pin be placed when asked to guess where billionaire philanthropists had declared their intention to cure, prevent or manage all human disease before the end of the century?It was clear from the start that the announcement from Priscilla Chan and her husband, Mark Zuckerberg, nudged at the boundaries of belief. Writing in praise in the US journal, Science, David Baltimore, a Nobel laureate at California Institute of Technology concedes the goal “may raise eyebrows”. Even Cori Bargmann, the renowned neurobiologist who will lead the charge, is aware how it might be perceived. It is “ambitious”, she says, “but not completely ridiculous”.It is tempting to dismiss the Chan Zuckerberg Initiative as hubris. But the best part of a century is a long time in medicine. Most babies born in 1900 did not live to see the age of 50. Medicine has not been the only reason for the dramatic rise in life expectancy since, but it was a crucial factor. “By 2100 we’ll be shocked by how much we’ve achieved, and we’ll be more shocked with initiatives like this,” says Jim Smith, chief of strategy at the UK’s Medical Research Council.If not hubris, then what about one-upmanship? Bill Gates wants to eradicate malaria in a generation. Elon Musk wants a Mars colony in a decade. Yuri Milner has set his sights on sending a spacecraft to a star at one-fifth the speed of light. How better to leave your mark higher on the wall than to make every human disease obsolete within your child’s lifetime? Or at least find a way to manage awful conditions, so they no longer mar people’s lives?But audacious goals are precisely what are needed. “We have to be bold about the scale of the challenge we face in improving human health,” says Steve Caddick, professor of chemical biology at University College London and director of innovation at the Wellcome Trust, the world’s largest biomedical research charity. “What is truly important about this kind of approach is that it creates the hope you need to go from exploratory science to making the world a better place.” He goes on: “Aspiration is essential. This idea that if we put our minds to it, almost anything is possible—that is what can sustain people through the peaks and troughs of decades of research.”42. .The underlined sentence in Paragraph 1 means that Silicon Valley entrepreneurs （）.43. .According to Cori Bargmann and David Baltimore, the Zuckerbergs’ project may be （）.44. .In Paragraph 3, the author emphasizes that （）.45. .In Paragraph 4, the author implies that ________ （）can leave the highest mark on the wall.46. .In Paragraph 5, “peaks and troughs” most likely means （）.47. Which of the following is the best title for the passage?

Security guard, truck driver, salesperson—year after year, these jobs appear on lists of the unhappiest careers. Although many factors can make a job dismal—unusual hours, low pay, no chance for advancement—these three gigs stand out for another reason: They’re characterized either by a lack of conversation or by obligatory but meaningless small talk.Psychologists have long said that connecting with others is central to well-being, but just how much conversation we require is under investigation. In one study, researchers eavesdropped on undergraduates for four days, then cataloged each overheard conversation as either “small talk” (“What do you have there? Popcorn? Yummy!”) or “substantive” (“So did they get divorced soon after?”). They found that the second type correlated with happiness—the happiest students had roughly twice as many substantive talks as the unhappiest ones. Small talk, meanwhile, made up only 10 percent of their conversation, versus almost 30 percent of conversation among the least content students.But don’t write off chitchat just yet. Scientists believe that small talk could promote bonding. Late last year, Princeton researchers reported that ring-tailed lemurs reserve their call-and-response conversations, akin to human chitchat, for the animals they groom the most. This suggests that small talk maintains closeness with loved ones, and isn’t merely the stuff of awkward exchanges with strangers.Still, bantering with strangers could brighten your morning. In a series of experiments, psychologists gave Chicago commuters varying directions about whether to talk with fellow train passengers—something they typically avoided. Those told to chat with others reported a more pleasant journey than those told to “enjoy your solitude” or to do whatever they normally would. None of the chatters reported being rebuffed. And the results held for introverts and extroverts alike—which makes sense, since acting extroverted has a positive effect on introverts.Of course, some of us are better than others at turning small talk into something bigger. In one study, people who were rated “less curious” by researchers had trouble getting a conversation rolling on their own, and had greater luck building closeness with others when they were supplied with questions that encouraged personal disclosure (“When did you last cry in front of someone?”). But people who were deemed “curious” needed no help transforming conversations about mundane things like favorite holidays into intimate exchanges. A “curious mind-set,” the authors concluded, can lead to “positive social interactions.”36. In Paragraph 1, the primary reason why the three jobs are the unhappiest is that （）.37. What can be inferred from Paragraph 2?38. The underlined sentence in Paragraph 3 indicates that （）.39. The conclusion drawn from Paragraph 4 is that （）.40. The underlined phrase in Paragraph 5 means （）.41. The author’s attitude towards “small talk” is （）.

One day in 1945, a man named Percy Spencer was touring one of the laboratories he managed at Raytheon in Waltham, Massachusetts, a supplier of radar technology to the Allied forces. He was standing by a magnetron, a vacuum tube which generates microwaves, to （21） the sensitivity of radar, when he felt a strange sensation. Checking his pocket, he found his candy bar had melted. Surprised and （22）, he sent for a bag of popcorn, and held it up to the magnetron. The popcorn popped. Within a year, Raytheon made a patent （23） for a microwave oven.The history of scientific discovery is peppered with breakthroughs that came about （24）. The most momentous was Alexander Fleming’s discovery of penicillin in 1928, （25） when he noticed how a mould that floated into his Petri dish killed off the surrounding bacteria. Spencer and Fleming didn’t just get lucky. Spencer had the nous and the knowledge to turn his observation into （26）; only an expert on bacteria （27） ready to see the significance of Fleming’s stray spore. As Louis Pasteur wrote, “In the field of observation, chance （28） only the prepared mind.”The word that best describes this subtle blend of chance and agency is “serendipity”. It was （29） by Horace Walpole, man of letters and aristocratic dilettante. Writing to a friend in 1754, Walpole explained an unexpected discovery he had just made by （30） to a Persian fairy tale, “The Three Princes of Serendip”. The princes, he told his correspondent, were “always making discoveries, by accidents and sagacity, of things which they were not （31） ... now do you understand Serendipity?” These days, we tend to （32） serendipity with luck, and we neglect the sagacity. But some conditions are more （33） to accidental discovery than others.Today’s world wide web has developed to organize, and make sense of, the exponential increase in information made （34） to everyone by the digital revolution, and it is amazingly good at doing so. If you are searching for something, you can find it online, and quickly. But a side-effect of this awesome efficiency may be a shrinking, （35） an expansion, of our horizons, because we are less likely to come across things we are not in quest of.

The administration is willing to negotiate（）but it is not ready to make any significant changes to the legislation.

Research has found that the drug contains a toxic chemical that can cause（）problems.

I am eager to share my thoughts with you, to compare（）, and to get your opinions.

Don’t be afraid to（）yourself in the interview.

His second statement agrees（）facts as stated by the other witnesses.

My old school friends are scattered far and（）now.

A dentist may decide to（）the tooth to prevent recurrent trouble.

He might have（）pressure to save his position.

Be sure to（）an enclosed shelter, especially if you intend to build a fire in it.

Few people believed that the Empire could continue unchanged after the（）of the war.

We felt as if half the people in town were（）our lives.

Nissan has unveiled its super-quiet, zero（）electric car technology, a key design for the company.

The solution is grossly oversimplified and is（）with your generally realistic attitude.

There are volumes of work examining how couples and families（）conflict, but very few studies examining them having fun and laughing together.

（） is piling up that as men do more of the caregiving, violence against women falls.

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