选择知识点

Race walking shares many fitness benefits with running,research show,while most likely contributing to fewer injuries.It does,however,have its own problem.
Race walkers are conditioned athletes.The longest track and field event at the Summer Olympics is the 50-kilometer race walk,which is about five miles longer than the marathon.But the sport's rules require that a race walkers knees stay straight through most of the leg swing and one foot remain in contact（接触）with the ground at all times.It's this strange form that makes race walking such an attractive activity,however,says Jaclyn Norberg,an assistant professor of exercise science at Salem State University in Salem,Mass.
Like running,race walking is physically demanding,she says.According to most calculations race walkers moving at a pace of six miles per hour would bum about 800 calories（卡路里）per hour,which is approximately twice as many as they would bum walking,although fewer than running,which would probably bum about 1，000 or more calories per hour.
However,race walking does not pound the body as much as running does,Dr.Norberg says.According to her research,runners hit the ground with as much as four times their body weight per step,while race walkers who do not leave the ground,create only about 1.4 times their body weight with each step.
As a result,she says,some of the injuries associated with running,such as runner's knee,are uncommon among race walkers.But the sports strange form does place considerable stress on the ankles and hips,so people with a history of such injuries might want to be cautious in adopting the sport.In fact,anyone wishing to try race walking should probably first consult a coach or experienced racer to learn proper technique,she says.It takes some practice.



Why are race walkers conditioned athletes？ ______

A. They must run long distances.
B. They are qualified for the marathon.
C. They have to follow special rules.
D. They are good at swinging their legs.

What advantage does race walking have over running？ ______

A. It's more popular at the Olympics.
B. It's less challenging physically.
C. It's more effective in body building.
D. It's less likely to cause knee injuries.

What is Dr Norberg's suggestion for someone trying race walking？ ______

A. Getting experts' opinions.
B. Having a medical checkup.
C. Hiring an experienced coach.
D. Doing regular exercises.

Which word best describes the author's attitude to race walking？ ______

A. Skeptical.
B. Objective.
C. Tolerant.
D. Conservative

In my everyday life,I am on an ongoing journey to figure out different ways to reduce my carbon footprint on the planet.A carbon footprint is the measure of influence our activities have on the environment,in particular climate change.It is calculated by the amount of greenhouse gas we produce in our daily lives.Fortunately,nowadays it is much easier to make eco-friendly lifestyle choices than,let's say,20 years ago.But one question has been on my mind a lot lately：is it better to buy new eco-friendly products or used traditionally produced goods？
After doing some research,I have decided that some things are better new and others are better used.Let me try to explain.
A carbon footprint is made up of two parts,the primary footprint and he secondary footprint.The primary footprint is a measure of our direct emissions（排放）of carbon dioxide（CO₂）from the burning of fuels,including household energy consumption and transportation.The secondary footprint is a measure of the indirect CO₂ emissions from the whole lifecycle of products we use-those related to their production and breakdown.
Based on this understanding,we have a good deal of control and responsibility over our carbon footprint.Things like dishes,clothes and furniture fall into the "second footprint" group,so less is more and we can focus on finding used goods to avoid the added production.However,for the car and the other appliances（设备）that we need we can go with new,energy-saving models.I heard somewhere that electronics and appliances ave or off 90% of their carbon footprint after they leave the factory.So it seems most reasonable to go for the energy-saving models.The main concern here is the amount of energy that goes into the making of new products and whether or not that extra carbon is worth the footprint the product will make once it gets to you.



What is the text mainly about？ ______

A. What appliances to buy to save energy.
B. What a carbon footprint means in our life.
C. How to identify different carbon footprints.
D. How to make eco-friendly lifestyle choices.

What do we know about the secondary carbon footprint？ ______

A. It is related to our consumption of fuels.
B. It is made when we are buying the products.
C. It is less harmful than the primary carbon footprint.
D. It is counted as ours though not directly made by us.

Which of the following helps reduce our carbon footprint according to the author？ ______

A. Using second-hand textbooks.
B. Using old and expensive cars.
C. Buying new but cheap clothes.
D. Buying new wooden furniture.

"The footprint" underlined in the last sentence refers to the CO₂ produced in ______ .

A. using the product
B. recycling the product
C. making the product
D. transporting the product

An advance in electronic publishing could make the e-book you are reading seem as dated as a silent film.Publishers hope to explore the growing success of e-books by releasing versions with added soundtracks（电影配音）and musical accompaniments.
The noises in the first multimedia books - released in Britain on Friday - include rain hitting a window in a Sherlock Holmes tale.When the plot of a book reaches the most exciting part,background scores will create tension.
Supporters argue that sound effects are the next logical development for e-books and will add excitement for younger readers.Critics,however,will argue that the noise will ruin the simple pleasure of having the imagination stimulated by reading.
Caroline Michel,chief executive of the literary agency,said the new generation of computer- literate readers was used to multiple sensory input.She said, "Young people have split computer screens where they may be watching television and replying to an email at the same time.If that's what the market wants then we should respond to the market."
Book track's sound effects work by estimating the user's reading speed.Each time you turn a page,the software reassesses where you have reached in the text and times the sounds to switch on accordingly.If the soundtrack becomes out of synch （同步），a click on any word will reset it.
Some authors fear that a soundtrack could destroy the peace and quiet of libraries and ruin the pleasure,of reading.David Nicholls,author of Our Day,the bestseller now released as a film,said, "This sounds like the opposite of reading.I have enough trouble reading an e-book because I'm constantly distracted by emails."
Stuart Mat Bride,the crime writer whose novel Shatter the Bones was an e-book bestseller,sells 18% of his books as electronic downloads.He said,"If I'm reading,I will do the noise in my head.I don't need someone to tell me what tea cups clinking sounds like.That would irritate（激怒）me."



What do publishers expect an e-book soundtrack to do？ ______

A. Help to release an e-book as a film.
B. Help readers improve reading speed.
C. Add tension at a book's exciting point.
D. Get readers familiar with the background.

Who is in favor of added soundtracks for e-books？ ______

A. Mr.Darcy.
B. Caroline Michel.
C. David Nicholls.
D. Stuart MacBride.

What do we know about Stuart MacBride？ ______

A. He was a person who was easy to get angry.
B. He knew a great deal about tea and tea culture.
C. Eighty-two percent of his books described crime.
D. He imagined sounds related to the story when reading.

What's the main idea of the passage？ ______

A. Opinions about e-books with soundtracks.
B. Response to the need of the book market.
C. Reasons for traditional e-books becoming outdated.
D. Suggestions on encouraging readers' imagination.

When you hear the beginning of your favorite song from the radio,suddenly your neck is covered in goose bumps （鸡皮疙瘩）.
It's such a thing that a group of scientists call "skin excitement"-a feeling of cold caused not by a drop in temperature or sudden scare,but by the sense of beauty. "Skin excitement" can come from a song,a painting,a moving movie scene,or even a beloved memory-pretty much anything that causes the giving out of pleasure soaked dopamine （多巴胺）in your brain.But it does not come for all of us.
Your favorite music uncovers a lot about your personality,and so does how you respond to that music.Studies suppose that as few as 55 percent of people experience："skin excitement" when listening to music.And if you count yourself among this group,the goose bumps on your skin aren't the only giveaway-scientists can read it in your brain,too.In a new study published in the journal Social Cognitive and Affective Neuroscience,Harvard researchers performed brain scans on 10 students who said they reliably got cold when listening to music,and 10 students who didn't.They found that the cold prone （容易发冷的）brains may really be excited by stronger emotions.
Cold-prone brains are generally more likely to show stronger emotional intelligence than no-cold brains.Cold- prone minds tend to have unusual active imagination,reflect more deeply on their emotions,and appreciate nature and the beauty of music and art to a stronger degree than no-cold brains.
So,what type of music causes the chills？It seems that the type is not so important；participants in the new study reported getting cold from songs of every kind.And any song connected with a strong emotional memory of the listener can produce the most reliable results.For me,that's the song Sailing to Philadelphia by Mark Knopfler,which I listened to as a kid in the car with my dad,on the way to the summer camp.



What can we learn about "skin excitement" in the text？ ______

A. It helps to produce dopamine.
B. It is caused by the pain in the skin.
C. It can be experienced by every music listener.
D. It is the human body's reaction to something nice.

What does the new study by Harvard researchers mainly find？ ______

A. The percentage of music lovers in students.
B. The solutions to the goose bumps on one's skin.
C. The differences between cold prone and no-cold brains.
D. The relationship between one's music preference and personality.

What are people with cold-prone brains like？ ______

A. Beautiful and intelligent.
B. Emotional and dishonest.
C. Imaginative and sensitive.
D. Brave and strong-minded.

Which of the following can be the best title for the text？ ______

A. Responses to Music Vary among People
B. A Feeling of Cold Is Caused by Horrible Music
C. Your Favorite Music Reveals Your Personality
D. Favorite Music May Bring Forth Goose Bumps

In recent years,Ethiopia has become a regional leader in solid waste management,Last year,the country transformed the landfill（垃圾填埋场）in Addis Ababa into a new waste-to-energy plant,the first such project on the continent.The plant incinerates up to 1，400 tonnes of waste every day,about 80 percent of the city's rubbish,supplying the capital with 25 percent of its household electricity needs.
However,despite these important steps,challenges remain in Ethiopia.Although the country has permitted the Basel,Stockholm and Rotterdam conventions,laws and policies for environmentally sound management of hazardous（有害的）wastes are still not effective in preventing littering waste illegally.
To help Ethiopia meet these challenges,the Chemicals and Waste Management Program is supporting the country with a three-year project to enhance its capacity for sound management of hazardous wastes.
In the initial stages,a project management unit will be formed,made up of many representatives from government departments and private organizations.This unit will be responsible for reviewing and assessing Ethiopia's current legal system,which,despite numerous advances in recent years,does not specifically target the recycling of hazardous waste.Once legal gaps are identified,the project will seek to update existing policies and strategies.
Many people in Ethiopia are not aware of the possible effect of environmental damage and the need to report such crimes to the police.To resolve this pressing issue,Ethiopia will be conducting a series of capacity-building activities,including creating awareness-raising programs,training trainers and providing equipment.
Ethiopia will also work to establish a national mechanism for chemicals and waste management by engaging government departments and civil society groups.Authorities will also make budgetary provisions（预算拨款）in national,regional and institutional planning to ensure funding for these activities is sustainable even after the project's completion.



Which can replace the underlined word "incinerates" in paragraph 1？ ______

A. produces
B. gathers
C. burns
D. absorbs

What's the main problem of Ethiopia in waste management？ ______

A. The funds are not sufficient.
B. The shortage of workers is severe.
C. The pollution level is too high.
D. The relevant laws are not sound.

What will Ethiopia do to help the natives protect the environment？ ______

A. Call on them to start some programs.
B. Raise their environmental awareness.
C. Reward them with budgetary provisions.
D. Restrict their environmental movement.

What does the text mainly talk about？ ______

A. Ethiopia is putting efforts into waste management.
B. Ethiopia is facing serious environmental problems.
C. Ethiopia has achieved success in waste management.
D. Ethiopia has reduced environmental pollution levels.

Here on Earth where most of us live,we spend about a third of everyday lying down sleeping and two-thirds standing or sitting in an upright position.
That's not really how it goes in space when people are weightless and the zero gravity environment causes more liquid to shift to the head.Faces get swollen,legs lose volume and appear to be smaller.Many astronauts have complained of eye and back problems after coming back down to Earth and its gravity.
And now scientists say they have discovered some new risks with long-term space flight.A study published recently in JAMA Network Open,a medical journal,examined 11 healthy astronauts who had been on the International Space Station for six months.Eight of them had unusual characteristics observed in their blood.For instance,six of the astronauts had reverse（反向的）blood flow from their heads.
The lead author of the study says he doesn't know if that's actually harmful.The blood is still leaving the head from other pathways,so flowing backwards through a jugular vein（颈静脉）may not be dangerous.But he says it does show a change in how blood moves through the body while in space.
Another issue the study found was blood clots（凝块）.One astronaut had one.Another showed signs of a partial blood clot.That is potentially harmful as the clots can block the flow of blood to the lungs.The astronaut who had one was treated for the rest of the spaceflight and made it home safely.
What does all this mean？Well,one researcher says these issues have probably been occurring since humans first went into space and that they would likely resolve themselves when astronauts came back down to Earth.Knowing about them now gives doctors something else to monitor when people leave our atmosphere.



What causes the physical problems for astronauts？ ______

A. Sleeping for a long time.
B. Staying in the spaceship.
C. The shift in their bodies.
D. The zero gravity environment.

How many issues did the study newly find？ ______

A. One.
B. Two.
C. Three.
D. Four.

What can we know about the blood clot？ ______

A. It is a common problem.
B. It was first found by astronauts.
C. It is a new kind of disease.
D. It is a threat to people's health.

What may be the best title for the text？ ______

A. Doctors have a new task for astronauts
B. Zero gravity stops astronauts flying in space
C. New risks are found in long-term space flight
D. It's dangerous for astronauts to fly into space

If you were to throw,say,a banana peel out of your car while driving along the motorway,that would be a completely harmless action,due to the fact that it's part of a fruit - right？Actually,no.A banana peel can take up to two years to be naturally processed,and with a third of motorists admitting to littering while driving,that's a whole lot of discarded banana peels.An orange peel and a cigarette butt has a similar biodegrading （生物降解）term to that of a banana peel,but tin cans last up to 100 years；and plastic bottles last forever,as do glass bottles.
Despite the fact that longer-lasting materials will serve to damage the environment and its animals for longer,we can't merely measure the severity of a certain type of rubbish by its lifetime.For example,despite having a fairly short length of biodegrading time,more than 120 tons of cigarette-related litter is discarded in the UK every day.
It's not a cheap habit either：to keep our streets clean annually costs UK taxpayers £500 million,and when you include our green spaces,that goes up to £1 billion.So,it's not surprising that if caught fly-tipping you could face a £20，000 fine or even jail time and,if you disposed of something dangerous,the court could give you five years to serve.Regardless of how severe these punishments might seem,however,among the reported cases only 2，000 were found guilty out of 825，000，so we still have some way to go in making sure people obey the rules.



What does the underlined word "discarded" in para 1 mean？ ______

A. Harmless.
B. Processed.
C. Thrown.
D. Long-lasting.

Which of the following has the longest biodegrading term？ ______

A. Glass bottles.
B. Tin cans.
C. Cigarette butts.
D. Banana peels.

What can be inferred from the passage？ ______

A. The severity of rubbish can be measured by its lifetime.
B. Quite a few people were found guilty of illegally littering.
C. Every year UK taxpayers spend £500 million keeping streets free of dirt.
D. Cigarette-related litter and peels can be ignored for their fairly short lifetime.

What is the purpose of the passage？ ______

A. To inform readers of different biodegrading terms.
B. To call for people not to litter illegally.
C. To encourage people to use fewer plastic bags.
D. To stress the importance of good behavior.

Light pollution is a significant but overlooked driver of the rapid decline of insect populations,according to the most comprehensive review of the scientific evidence to date.
Artificial light at night can affect every aspect of insects' lives,the researchers said. "We strongly believe artificial light at night - in combination with habitat loss,chemical pollution,invasive species,and climate change - is driving insect declines, " the scientists concluded after assessing more than 150 studies.
Insect population collapses have been reported around the world,and the first global scientific review published in February,said widespread declines threatened to cause a "catastrophic collapse of nature's ecosystems".
There are thought to be millions of insect species,most still unknown to science,and about half are active at night.Those active in the day may also be disturbed by light at night when they are at rest.
The most familiar impact of light pollution is moths（飞蛾）flapping around a bulb,mistaking it for the moon.Some insects use the polarisation of light to find the water they need to breed,as light waves line up after reflecting from a smooth surface.But artificial light can scupper （使泡汤）this.Insects are important prey （猎物）for many species,but light pollution can tip the balance in favour of the predator if it traps insects around lights.Such increases in predation risk were likely to cause the rapid extinction of affected species,the researchers said.
The researchers said most human-caused threats to insects have analogues in nature,such as climate change and invasive species.But light pollution is particularly hard for insects to deal with.
However,unlike other drivers of decline,light pollution is relatively easy to prevent.Simply turning off lights that are not needed is the most obvious action,he said,while making lights motion-activated also cuts light pollution.Shading lights so only the area needed is lit up is important.It is the same with avoiding blue-white lights,which interfere with daily rhythms.LED lights also offer hope as they can be easily tuned to avoid harmful colours and flicker rates.



What is the 5th paragraph mainly about？ ______

A. How light travels in space.
B. How light helps insects find food.
C. How the food chain is interrelated.
D. How light pollution affects insects.

What does the underlined word "analogues" in Paragraph 6 probably mean？ ______

A. Selective things.
B. Similar things.
C. Variations.
D. Limitations.

What is the purpose of the last paragraph？ ______

A. To offer solutions.
B. To give examples.
C. To make comparisons.
D. To present arguments.

What is discussed in the passage？ ______

A. Causes of declining insect populations.
B. Consequences of insect population collapses.
C. Light pollution：the key bringer of insect declines.
D. Insect declines：the driver of the collapsed ecosystem.

As paleontologists can tell, Neanderthals （尼安德特人）died out around 40，000 years ago. But they did not vanish from the Earth entirely. In the past decade it has become clear that Neanderthals mated with the ancestors of modern humans, and that some of those unions produced offspring （generations to follow）. The result is that almost half of the Neanderthal genome survives, spread in small quantities among most modern people's DNA. The exception is those with mostly African ancestors, for Neanderthals seem never to have lived in Africa.
Such genes have been associated with everything from hairiness to fatness. Many seem to be related to the immune system, and to affect the risk of developing diseases including lupus, Crohn's disease and diabetes.
A pair of recent papers suggest Covid-19 belongs on that list as well. Two long DNA strings, both inherited from Neanderthals, appear to have resistance or sensibility to severe Covid-19， depending on which is present.
The work was led by Hugo Zeberg and Svante Paabo at the Max Planck Institute for Evolutionary Anthropology in Leipzig, whose researchers pioneered the study of Neanderthal DNA.
Their first paper, published in Nature in September, described one Neanderthal DNA string, known as a "haplotype"（单体型），which is associated with a higher risk of serious illness.
Having one copy of the haplotype, which is found on the third of the 46 chromosomes possessed by humans, doubles the chances of a trip to intensive care. Those unlucky enough to possess two copies, one from each parent, face an even higher risk.
That genetic bad luck is not evenly distributed. It is most common among people of South Asia, with 63 percent of the population of Bangladesh carrying at least one copy； and among Europeans, where the rate is around 16 percent. As expected, it is almost absent from Africa. More strikingly, it is also very rare in Eastern Asia.
Exactly what the haplotype does is not clear. One gene within it affects a protein that interacts with the cellular receptors （细胞受体）that SARS-CoV-2 （the virus which causes Covid-19）uses to enter cells and control them.
The haplotype is also thought to be involved in the production of signalling proteins,called cytokines,which help to regulate the immune system. An overly aggressive immune response is one mechanism by which Covid-19 kills.



Who are the most likely to carry the haplotype according to the study？ ______

A. Eastern Asians.
B. Africans.
C. Europeans.
D. South Asians.

What can we learn about the study？ ______

A. The haplotype is equally distributed among people in different races.
B. Covid-19 kills partly because the immune system responds to SARS-CoV-2 abnormally.
C. The haplotype appears to have resistance or sensibility to severe Covid-19.
D. People unlucky to have two copies of the haplotype are sure to suffer from serious illness.

What is the main idea of the last two paragraphs？ ______

A. Why the Neanderthal genome is related to a higher risk of serious illness.
B. What effects the haplotype has on different people in different races.
C. Why the haplotype makes people have a higher risk of Covid-19.
D. What the haplotype does to affect and regulate the immune system.

What will the author probably write in the next paragraph？ ______

A. The second study on Covid-19.
B. The previous study about Neanderthals.
C. The other Neanderthal DNA string.
D. The sensibility to severe Covid-19.

In June,11-year-old Nigerian ballet dancer Anthony Mmesoma Madu was filmed barefoot,spinning and leaping gracefully in the air and landing in concrete,rain puddles（水坑）.Just a few short months later,he has become an Internet star and gained a famous scholarship in America.
Madu thought he was being recorded for a study session by his ballet instructor,instead,the short video practicing his moves was posted on social media and has been shared widely across the world,with of his fans including Hollywood actors Cynthia Erivo and Viola Davis.
His dancing also caught the attention of Cynthia Harvey,the artistic director of the ABT Jacqueline Kennedy Onassis School of Dance in New York.Harvey was so impressed by his talent that she tracked him down and offered him a scholarship with the American Ballet Theatre where he will attend a summer school in 2021.
Madu says his interest in ballet developed after watching Barbie in the 12 Dancing Princesses,a 2006 cartoon about 12 princesses who share a passion for the dance. "When I was watching the cartoon,I told my mum that I want to do ballet," he said
He eventually got the chance to learn the dance after relocating to Ojo,a suburb（郊区）of Lagos with his mother,where they met Daniel Owoseni Ajala,founder of the Leap of Dance Academy.Ajala founded the dance academy in 2017 and has been teaching ballet for free to children who are unable to pay for a dance education since then.
When the self-taught instructor learned of Madu's desire to dance,he said he encouraged Madu's mother to let him sign up.It was during one of their sessions that he recorded Madu's dance video,but he never imagined that it would circulate rapidly.
"The video wasn't something we imagined to come out the way it did.It was just something that was supposed to show corrections of movements.It was bigger than I imagined,and I started getting calls.Celebrities were posting us," he said.



What can we know about Anthony Mmesoma Madu？ ______

A. He decided to apply for a scholarship.
B. He became one of Viola Davis' big fans.
C. He posted his short video on social media.
D. He impressed many people by his dancing.

When did Madu show interest in ballet？ ______

A. After attending a dance academy.
B. After moving to a suburb of Lagos.
C. After watching a lively cartoon.
D. After meeting Daniel Owoseni Ajala.

How can we describe Daniel Owoseni Ajala？ ______

A. Demanding but sympathetic.
B. Warm-hearted and respectable.
C. Stubborn but generous.
D. Creative and outstanding.

Which can be a suitable title for the text？ ______

A. A Non-profit Dance Academy
B. A Wonderful Dance Performance
C. A Self-taught Ballet Instructor
D. An 11-year-old Nigerian Ballet Boy