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,which scientists says because once ecosystems pass their tipping point(临界点),it is remarkably difficult for them to return.
1.What have scientists discovered with the help of mathematical models of food webs?
A.The living habits of species in food webs.
B.The rules governing food webs of the ecosystems.
C.The approaches to studying the species in the ecosystems.
D.The differences between weak and strong links in food webs.
2.A strong link is found between two species when a predator______
A.has a wide food choice B.can easily find new prey
C.sticks to one prey species D.can quickly move to another place
3.What conclusion can be drawn from the examples in Paragraph 4?
A.Uncontrolled human activities greatly upset ecosystems.
B.Rapid economic development threatens animal habitats.
C.Species of commercial value dominate other species.
D.Industrial activities help keep food webs stable.
4.How does an early-warning system help us maintain the ecological balance?
A.By getting illegal practices under control.
B.By stopping us from killing large predators.
C.By bringing the broken-down ecosystems back to normal.
D.By signaling the urgent need for taking preventive action.
高三英语阅读理解困难题查看答案及解析
You can’t walk into the office without Rihanna’s voice singing “work work work work work work” in your head. And that one line from Lady Gaga’s “Bad Romance” still makes you want to scream. These are commonly known as earworm songs—those sticky tunes that continue to play in your head. A recent study finds that more than 90% of adults report hearing earworm songs on a weekly basis.
Fortunately, most people report earworm songs as pleasant. But others find them annoying or even maddening. “Some people are troubled by them to the point that it disturbs life,” says Elizabeth Hellmuth Margulis, a professor at the University of Arkansas who has studied earworm songs.
Margulis says earworm songs tend to have some predictable characteristics. For one thing, they tend to small parts of a song—not the whole track. And “the songs you’ve heard recently also have the most possibility to get stuck in your memory,” she says.
But sometimes something strange and unpredictable can also start a track paying in your head. “Once I was at the doctor’s office and saw a poster of a man who I thought looked like Gaston—a character from Beauty and the Beast,” Margulis recalls. A couple minutes passed, and she realized she couldn’t get “Be Our Guest”, the song in the movie, out of her head, even though she hadn’t thought of the tune in years. In that instance, she was able to identify her earworm’s trigger: the Gaston-looking man in the poster. “But the connections can be really unclear,” she says.
Margulis points out that, in all of human history, recorded music is a very new phenomenon. She says some have inferred that earworm songs are also new—the unintended consequence of being able to hear the same song played everywhere in the same way over and over again. So far, the convincing explanation for why human beings experience earworm songs remains a mystery. But there are some well-established ways to cast off the earworm songs.
“Finding a mentally demanding task and putting your mind on it usually shifts attention away from internal music. People tend to get earworms when performing tasks that don’t require their full attention—stuff like doing the dishes,” Margulis says.
Chewing gum can also help. When a song is stuck in our heads, it’s almost like we’re singing along with it. If you make your mouth do something else—chewing gum, eating a meal or talking with a friend—that can kick out the earworm.
You could also face your enemy. By listening to the full track that includes the passage stuck in your head, you may find “closure” and relief.
1.Which of the following is most likely to be an earworm song?
A.A song made up of simple words.
B.A song heard frequently these days.
C.A song sung by a most famous singer.
D.A song learned during one’s childhood.
2.What does the underlined word “trigger” in Paragraph 4 mean?
A.Type. B.Tune.
C.Cause. D.Characteristic.
3.We can infer that earworm songs may ________.
A.result from modern technology B.be experienced over meals
C.help regain lost memories D.hurt one’s hearing
4.What is mainly talked about in the last three paragraphs?
A.Why we hear earworm songs. B.Where to find earworm songs.
C.When we hear earworm songs. D.How to get over earworm songs.
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Recently, researchers at the University of Toronto figured out a way with a quick video selfie to accurately measure blood pressure with your smartphone’s camera by developing a technology known as transdermal optical imaging (TOI)(透皮光学成像).
Cameras on smartphones can catch red light reflected from hemoglobin (血红素)under our skin, which permits TOI to visualize and measure blood flow changes. Researchers measured the blood pressure of 1,328 Canadian and Chinese adults by getting two-minute videos of their faces on an iPhone. “From the video got by the technology, you can see how the blood flows in different parts of the face and through this flow, you can get a lot of information,” said Kang Lee, lead author of the study.
Lee also helped create an app called Anura, which allows people to try out the TOI software for themselves, giving them the ability to record a 30-second video of their face and receive measurements for stress levels and resting heart rate. Lee said more research was needed to make sure that the measurements were as accurate as possible, explaining that the study didn’t test people with very dark or very fair skin.
“In order to improve our app to make it usable, particularly for people with hypertension (高血压),we need to collect a lot of data from them, which is very hard because a lot of them are already taking medicine,” Lee explained. “We cannot tell them not to take medicine, but from time to time, we get participants who don’t take medicine so we can get hypertensive people this way.”
The scientists said there were many potential applications of the technology, including providing health services for those who lived in remote areas.
1.What is mainly talked about in Paragraph 2?
A.Information offered by TOI. B.New findings on hypertension.
C.How TOI is put into smart phones. D.How the TOI technology works.
2.What might people benefit from the new technology mentioned above?
A.Living a life free from stress. B.Improving the heart function gradually.
C.Accessing health services for free. D.Knowing abnormal blood pressure earlier.
3.What can be done for a better Anura?
A.Equipping phones with better cameras.
B.Allowing phones to record longer videos.
C.Collecting data from more diverse samples.
D.Persuading participants not to take medicine.
4.Why does the author write this text?
A.To predict future applications of TOI.
B.To introduce TOI and an app related.
C.To describe functions of cameras on phones.
D.To evaluate the quality of an app called Anura.
高三英语阅读理解困难题查看答案及解析
America’s first transcontinental railroad, completed 150 years ago today at Promontory Summit in Utah, connected the vast United States and brought America into the modern age. Chinese immigrants contributed greatly to this notable achievement, but the historical accounts that followed often ignored their role.
Between 1863 and 1869, as many as 20,000 Chinese workers helped build the dangerous western part of the railroad, a winding ribbon of track known as the Central Pacific. At first, the Central Pacific Railroad’s directors wanted a whites-only workforce. When not enough white men signed up, the railroad began hiring Chinese men for the backbreaking labor. Company leaders were skeptical of the new recruits’ ability to do the work, but they proved themselves not only capable but even superior to the other workers.
Chinese workers cut through dense forests, filled deep narrow steep-sided valley, constructed long trestles(高架桥) and built enormous retaining walls(防护墙) -- some of which remain complete and undamaged today. All work was done by hand using carts, shovels and picks but no machinery. However, progress came at great cost: an estimated 1,200 Chinese laborers died along the Central Pacific route.
Despite these facts, Chinese workers were often left out of the official story because of their identity of foreigners. On the transcontinental railroad's 100th birthday, the Chinese workers were still not honored. It was another fifty years later that their role was gradually highlighted. To celebrate the railroad’s 150th anniversary in 2019, the California assembly passed a resolution in 2017 to recognize and honor the Chinese railroad workers by designating May 10, 2017, and every May 10 thereafter, as California Chinese Railroad Workers Memorial Day.
1.What might be the best title for the text?
A.The Birth of the Central Pacific Cost Dearly
B.May 10--A Special Day for Chinese Immigrants
C.Chinese Workers’ Contributions Gained Recognition
D.The 150th anniversary of the Central Pacific Railroad
2.What does “they” in Paragraph 2 refer to?
A.Chinese laborers. B.White workers.
C.Company leaders. D.Railroad directors.
3.Why does the author make such detailed descriptions in Paragraph 3?
A.To prove Chinese workers’ superior skills.
B.To stress the danger and difficulty of the work.
C.To describe the grand scenery along the railroad.
D.To show notable achievements made by Chinese workers.
4.What does the text intend to tell us?
A.None so blind as those who won’t see. B.No pains, no gains.
C.Truth will come to light sooner or later. D.Doing is better than saying.
高三英语阅读理解困难题查看答案及解析
We’ve all had cases where we’ve waited just a bit too long to pay an electric bill or speeding ticket. But one man, from California by reasonable assumption,who goes by “Dave”,recently took procrastination (拖延) one step further, by paying a parking ticket almost a half-century after it was given.
In December 2018, the Minersville Police Department in Pennsylvania received a letter in the mail. Whoever wrote the letter decided it was best to keep his name somewhat unknown,so he put the return address as “Wayward Road,Anytown California” under the name “Feeling guilty”.
When the officers opened the envelope,they found a brief letter, along with a $5 bill, and a parking ticket dating all the way back to 1974. The note read,“Dear PD,I've been carrying this ticket around for 40 plus years always intending to pay. Forgive me if I don't give you my info. With respect,Dave.”
Even though the initial parking ticket was only for $2, “Dave” must have felt awfully guilty because he left 150 percent,or $3, in interest.
Michael Combs, the Police Chief of the Minersville Police Department, stated in an interview that the same ticket would cost about $20 if it were given today. Combs went on to share that the original ticket from 1974 was given to a vehicle that had an Ohio license plate.
Because there was no system for tracking tickets given to out-of-state cars back then,“Dave” could have gotten away with never paying the $2 fine. But apparently,guilt got the best of him,and he decided to finally cough up the money more than 40 years past its due date.
1.How much do we know about “Dave”?
A. He lives in Wayward Road,Anytown California.
B. His car probably came from Ohio at that time.
C. The police are trying to find out more about him.
D. “Dave” is of course the man’s real name indeed.
2.Why didn’t “Dave” pay for the parking ticket until recently?
A. He completely forgot about it in the past 44 years.
B. He didn’t find it until almost half a century later.
C. He didn’t pay for it just because of procrastination.
D. He failed to find out who he should pay the money to.
3.What drove “Dave” to pay for the parking ticket at last?
A. A strong sense of guilt.
B. Fear of being tracked by the police.
C. Worry about being fined more.
D. Sudden change of his financial situation.
4.Which of the following can be the best title?
A. Police Chief of the Minersville Police Department Shares a Story
B. Parking Ticket Carried Around for Almost Half a Century from Ohio
C. Unusual Letter Comes from Wayward Road, Anytown California
D. Mysterious Procrastinator Finally Pays 44-Year-Old Parking Ticket
高三英语阅读理解困难题查看答案及解析
Sometimes it’s hard to let go. For many British people, that can apply to institutions and objects that represent their country’s past-age-old castles, splendid homes… and red phone boxes.
Beaten first by the march of technology and lately by the terrible weather in junkyards (废品场), the phone boxes representative of an age are now making something of a comeback. Adapted in imaginative ways, many have reappeared on city streets and village greens housing tiny cafes, cellphone repair shops or even defibrillator machines (除颤器).
The original iron boxes with the round roofs first appeared in 1926. They were designed by Giles Gilbert Scott, the architect of the Battersea Power Station in London. After becoming an important part of many British streets, the phone boxes began disappearing in the 1980s, with the rise of the mobile phone sending most of them away to the junkyards.
About that time, Tony Inglis’ engineering and transport company got the job to remove phone boxes from the streets and sell them out. But Inglis ended up buying hundreds of them himself, with the idea of repairing and selling them. He said that he had heard the calls to preserve the boxes and had seen how some of them were listed as historic buildings.
As Inglis and, later other businessmen, got to work, repurposed phone boxes began reappearing in cities and villages as people found new uses for them. Today, they are once again a familiar sight, playing roles that are often just as important for the community as their original purpose.
In rural areas, where ambulances can take a relatively long time to arrive, the phone boxes have taken on a lifesaving role. Local organizations can adopt them for l pound, and install defibrillators to help in emergencies.
Others also looked at the phone boxes and saw business opportunities. LoveFone, a company that advocates repairing cellphones rather than abandoning them, opened a mini workshop in a London phone box in 2016.
The tiny shops made economic sense, according to Robert Kerr, a founder of LoveFone. He said that one of the boxes generated around $13,500 in revenue a month and cost only about $400 to rent.
Inglis said phone boxes called to mind an age when things were built to last. I “like what they are to people, and I enjoy bringing things back,” he said.
1.The phone boxes are making a comeback ______.
A.to form a beautiful sight of the city
B.to improve telecommunications services
C.to remind people of a historical period
D.to meet the requirement of green economy
2.Why did the phone boxes begin to go out of service in the 1980s?
A.They were not well-designed. B.They provided bad services.
C.They had too short a history. D.They lost to new technologies.
3.The phone boxes are becoming popular mainly because of ______.
A.their new appearance and lower prices B.the push of the local organizations
C.their changed roles and functions D.the big funding of the businessmen
高三英语阅读理解困难题查看答案及解析
Eliud Kipchoge’s extraordinary sub-two-hour marathon in Vienna on Saturday is one of the greatest sporting achievements—recording a time that has never been achieved before, again. It is a time on the fringes (边缘) of what scientists believe is humanly possible.
“It is a great feeling to make history in sport after Sir Roger Bannister in 1954. I am the happiest man in the world to be the first human to run under two hours and I can tell people that no human is limited,” Kipchoge said afterwards.
Is he right? Where are the limits of human ability? And how close are we to reaching them?
Raph Brandon, head of science for England cricket, distinguishes between achievements which are constrained (限制) by human anatomy (解剖学), and those which require human determination or skill.
“When Bolt ran 9.58 in Berlin 10 years ago, if you analyse the split times it’s very hard to imagine where the improvement comes from,” said Brandon, “The Usain Bolt 100m or the two-hour marathon, they’re in that category.”
Multi-day, ultra-endurance events, such as Thomas’s cross-Channel swim, are different, Brandon said.
“They need determination, psychology and bloody-mindedness to go that little bit further. Those people will continue to do unique things because you’re not really taking the body to its anatomical limit. It’s more a question of how much you’re prepared to consume and exhaust yourself.”
And there’s a third category, those sporting endeavours (努力) that rely on hand-eye coordination: the goal tallies of Cristiano Ronaldo and Lionel Messi, and the batting of Virat Kohli Steve Smith or Don Bradman, who trained by hitting a golf ball with a stump against a wall to become the best batsman ever to play Test cricket.
Equipment has been a factor for many sports. NFL receivers wear gloves that enable them to make improbable one-handed catches. The GB cycling team swept the board at the Olympics because of their amazing new clothing tech.
The line between what is fair and unfair is blurry. Kipchoge’s sub-two-hour run will not be officially recognized. He ran behind a car which beamed a green laser on to the ground in front of him. Teams of pacemakers, 41 in total, ran in a v-formation to protect him from headwinds (逆风). He wore specially designed shoes and the time and date of the event were picked only after detailed weather forecasting.
Jo Davies, a sport psychologist, says recent studies have shown athletes can push themselves harder because of their perception of exhaustion.
Other research published this year which looked at athletes who had won multiple gold medals found that they were different in several important ways. They had often had a shocking and upsetting life experience and had suffered significant setbacks in their performance during their careers, as well as personality traits of determination, perseverance and perfectionism.
So whether or not those limits have been reached, there will be no shortage of people prepared to try to go beyond them.
1.Why is Eliud Kipchoge’s sub-two-hour marathon considered extraordinary?
A.It was made in Vienna on a weekend.
B.It pushed the limits of human ability.
C.It proved that there was no boundary of his achievements.
D.It was greater than the record kept by Sir Roger Bannister.
2.The Usain Bolt 100m and the two-hour marathon belong to the same category in that ________.
A.they need great determination or skills B.they can be achieved via equipment
C.they rely on hand-eye coordination D.they are reaching anatomical limit
3.Kipchoge’s sub-two-hour marathon will not be officially recognized because ________.
A.he was followed by pacemakers B.he was caught in headwinds
C.he got much special help D.he didn’t run on the picked day
4.It can be inferred from the last three paragraphs that ________.
A.Jo Davies believes that athletes make progress in the same way
B.anatomical limit prevents athletes from having sad life experience
C.an athlete who has suffered setbacks will win gold medals
D.whether an athlete can succeed or not may depend on himself
高三英语阅读理解困难题查看答案及解析
Deep in the middle of Sri Lanka, a massive column of rock reaches out from the green tropical forest. It is 660 feet tall and features frescoes (壁画), graffiti, and landscaped gardens.
The rock is known as Sigiriya and holds a special place in the island's cultural history.
It was established as the stronghold of a king over 1,500 years ago, and today the Sigiriya complex stands as one of the earliest preserved examples of ancient urban planning.
Located in the Central Province, the column of rock is somewhat central to the country. The rock is known as Sihagiri, meaning "Lion Rock", a nod to the giant animal carved from stone which greeted visitors at the entrance.
In 476 BC. King Dhatusena ruled over Sri Lanka. One of his illegal sons, Kashyapa, wanted the throne (王位). Kashyapa overthrew Dhatusena and drove his brother Moggallana to Southern India. Kashyapa crowned himself king in 477 BC.
King Kashyapa chose Sigiriya as his palace because its position was an advantage to the defensive stronghold, offering fantastic 360-degree views. Plans to build a city quickly unfolded and after several years, the Sigiriya complex had become a business center for the new King.
Sigiriya was both a palace and a fortress (堡垒); the overall complex featured five gates and measured just under 3 km by just over 1 km. The site plan consisted of a fort,an upper palace on the top of the rock,and lower palaces at ground level. The king also constructed gardens throughout,and for protection a river with walls surrounded the complex.
Frescoes decorate the western side of the rock, along with the mirror wall, a brick face covered in a highly-polished white plaster. When new, the wall was said to be able to produce Reflections.
Over time the Mirror Wall became a graffiti board, covered in verses written by visitors. Known as "Sigiri Graffiti", some of the messages date to the 8th century CE.
1.It is implied in the passage that Sigiriya was built to ______________.
A.preserve the culture of Sri Lanka B.prove the ancient urban planning
C.keep the King from being attacked D.protect the green tropical forest
2.According to the passage, some visitors would _________.
A.have a reflection before the Mirror Wall
B.leave comments on the Mirror Wall
C.draw beautiful paintings of girls on the wall
D.be lost in thought before the Mirror Wall
3.What do we know about Sigiriya?
A.Its entrance is carved like a lion. B.Its gardens are at ground level.
C.Its western side is a mirror. D.Its palaces are on the top of the rock.
4.What is the best title of the passage?
A.The giant lions in Sri Lanka. B.The pearl of the Indian Ocean.
C.The Lion Rock of Sri Lanka. D.The mirror wall in a rock.
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Challenging work that requires lots of analytical thinking, planning and other managerial skills might help your brain stay sharp as you age, a study published Wednesday in the journal Neurology suggests.
Researchers from the University of Leipzig in Germany gathered more than 1, 000 retired workers who were over age 75 and assessed the volunteers’ memory and thinking skills through a battery of tests. Then, for eight years, the scientists asked the same group to come back to the lab every 18 months to take the same sorts of tests.
Those who had held mentally stimulating(刺激), demanding jobs before retirement tended to do the best on the tests. And they tended to lose cognitive(认知) function at a much slower rate than those with the least mentally challenging jobs. The results held true even after the scientists accounted for the participants’ overall health status.
“This works just like physical exercise, ” says Francisca Then, who led the study. “After a long run, you may feel like you’re in pain, you may feel tired. But it makes you fit. After a long day at work-sure, you will feel tired, but it can help your brain stay healthy. ”
It's not just corporate jobs, or even paid work that can help keep your brain fit, Then points out. A waiter’s job, for example, that requires multitasking, teamwork and decision-making could be just as stimulating as any high-level office work. And “running a family household requires high-level planning and coordinating(协调), ” she says. “You have to organize the activities of the children and take care of the bills and groceries. ”
Of course, our brains can decline as we grow older for lots of reasons-including other environmental influences or genetic factors. Still, continuing to challenge yourself mentally and keeping your mind busy can only help.
1.Why did the scientists ask the volunteers to take the tests?
A.To assess their health status. B.To evaluate their work habits.
C.To analyze their personality. D.To measure their mental ability.
2.How does Francisca Then explain her findings in paragraph 4?
A.By using an expert’s words. B.By making a comparison.
C.By referring to another study. D.By introducing a concept.
3.Which of the following is the best title for the text?
A.Retired Workers Can Pick Up New Skills
B.Old People Should Take Challenging Jobs
C.Your Tough Job Might Help Keep You Sharp
D.Cognitive Function May Decline As You Age
高三英语阅读理解困难题查看答案及解析
The first patient who died on my watch was an older man with a faulty heart — the main pump had failed and his heart was beating irregularly and far too fast. We tried to slow it down with treatment, but it suddenly stopped beating completely. Later, whenever I would have a case like that one, I found myself second-guessing my clinical management. However, it turns out that thinking twice may actually cause more harm than good.
In a working paper, Emory University researchers found that when doctors delivering a baby have an adverse outcome, they are more likely to switch to a different delivery method with the next patient, often unnecessarily and sometimes with worse results.
Because doctors make so many decisions that have serious consequences, the fallout from second-guessing looms especially large for us. A 2006 study found that if a patient had a bleed after being prescribed warfarin, the physician was about 20% less likely to prescribe subsequent patients the blood thinner that prevents strokes. However, if a patient had a stroke and was not on warfarin, physicians were still no more likely to prescribe warfarin to their other patients.
These findings highlight interesting behavioral patterns in doctors. In the blood-thinner study, doctors were more affected by the act of doing harm (prescribing a blood thinner that ended up hurting a patient) and less affected by letting harm happen (not prescribing a blood thinner and the patient having a stroke). Yet a stroke is often more permanent and damaging than a bleed.
But this phenomenon is not unique to medicine. “Overreaction to Fearsome Risks” holds true for broader society.
For instance, sensational headlines about shark attacks on humans in Florida in 2001 caused a panic and led the state to prohibit shark feeding expeditions. Yet shark attacks had actually fallen that year and, according to the study, such a change was probably unnecessary given the extremely small risk of such an attack happening.
Humans are susceptible to emotional and often irrational thinking when processing information, adverse events and mistakes. As much as we don’t want to cause an unfortunate event to recur — in a medical setting or in the wider world — we need to be aware that a worst case scenario doesn’t necessarily mean we did anything wrong. When we overthink, we fail to rely on thinking based on what we know or have experienced. Instead, we may inadvertently overanalyze and come to the wrong conclusion.
I have treated dozens of patients who presented with the same illnesses as my first patient, who died more than a year ago. Instead of second guessing myself, I trusted my clinical instinct and stayed the course. Every one of those patients survived. You should trust your instinct in your life, too.
1.The first two paragraphs suggest that ______
A.Bad medical outcomes affect doctors.
B.Delivering babies can be difficult work.
C.Some doctors are not very experienced.
D.Doctors sometimes make silly mistakes.
2.In the blood-thinner study, doctors ______.
A.tend to prescribe less effective medicine
B.are more concerned about the patients’ safety
C.believe a stroke is more treatable than a bleeding
D.become less confident in writing certain prescriptions
3.The author develops his idea mainly by ______.
A.giving examples B.making comparisons
C.using metaphors D.quoting famous sayings
4.The author will probably agree that ______.
A.we shouldn’t doubt our own decisions
B.our experience will pave way for our future
C.humans are emotional and irrational on the whole
D.instincts don’t necessarily lead to wrong directions
高三英语阅读理解困难题查看答案及解析