Dandelion (蒲公英) seeds can travel for miles before finally floating down and settling somewhere new. Researchers recently discovered how the plants decide to spread. “We noticed that the dandelion parachute (降落伞) is closed in foggy mornings but then open again when the sun is up during the day,” according to Naomi Nakayama, a researcher of bioengineering. “The dandelion uses a bunch of hairs to improve air drag and aid its flight. Unlike insects or birds, they don’t need any energy input to fly a long distance- even hundreds of kilometers—they simply catch the wind.”
Researchers discovered the parachutes open and close using what they say is like an actuator (触动器), a device that changes energy and signals into movement. But this actuator doesn’t use any energy. The middle of the dandelion’s parachute is able to sense the amount of humidity (湿度) by absorbing water molecules (分子) in the air. Using signals about humidity information, they either open their parachutes and fly off or they close them and stay where they are.
“The center of the parachute changes its shape, moving the hairs altogether in harmony,” Nakayama says. “It’s basically a sponge made of no-longer living plant cells, which are arranged in a tube empty inside. The inner side and the outer side swell with water to different degrees, and that drives the movement.”
Knowing what causes dandelions to spread their seeds could help scientists learn how they deal with climate change. They say understanding the response could help researchers design new soft robots, which are those made from flexible materials that imitate soft bodies. “How plants move their body parts are different from animals and a simple, localized expansion could be enough to move arms,” Nakayama says. “Movement of a few arms has been achieved, but this is the first of many arm actuators. It is simple in design, so there is a lot of space for biomimicry (仿生学)”.
1. What makes the dandelion fly?A.Energy. | B.Wind. | C.Fog. | D.Parachute. |
A.By spreading their seeds. | B.By changing energy into movement. |
C.By feeling humidity information. | D.By staying where they are. |
A.Scientists make a robot out of dandelion. | B.Plants move just like the animals. |
C.Dandelions move with arms. | D.Plants can inspire biomimicry. |
A.Observing Dandelions | B.Dandelions and Climate Change |
C.Making Soft Robots | D.Dandelions and Biomimicry |
相似题推荐
【推荐1】Self-talk helps us all
Talking to yourself may seem a little shameful. If you've ever been overheard criticizing yourself for a foolish mistake or practicing a speech, you'll know the social problems it can cause.
But there's no need for embarrassment. Talking to ourselves, whether out loud or silently in our heads, is valuable. Far from being a sign of insanity, self-talk allows us to plan what we are going to do, manage our activities and control our emotions.
For example, take a trip to any preschool and watch a small girl playing with her toys. Your are very likely to hear her talking to herself: offering herself directions and talking about her problems.
As children, according to the Russian Psychologist LevVygotsky, we use private speech to control our actions in the same way that we use public speech to control the behavior of others. As we grow older, we keep this system inside.
Psychological experiments have shown that this so-called inner speech can improve our performance in tasks like telling what other people are thinking. Our words give us an interesting view of our actions. One recent study suggested that self-talk is most effective when we talk to ourselves in the second person: as "you" rather than "I".
Talking to ourselves seems to be a very good way of solving problems and working through ideas. Hearing different points of view means our thoughts can end up in different places, just like a regular dialogue, and might turn out to be one of the keys to human creativity.
Both kinds of self-talk -- silent and out loud -- seem to bring many different benefits to our thinking.
A.When something comes from within you, you always try your best to analyze it in a scientific way. |
B.Psychologists call this private speech -- language that is spoken out loud but directed at yourself. |
C.So words to the self, spoken silently or aloud, are so much more than just chatter. |
D.We keep the private speech we use as children inside -- but we never truly put away the out-loud version. |
E.According to the well-known saying, talking to yourself is the first sign of madness. |
F.Self-talk is efficient because when we are vocal about our thoughts, it makes a larger impact on our brain. |
【推荐2】Outdoor lighting in general poses a deadly threat to insects. That’s according to a study published online in November 2019 in the journal Biological Conservation, entitled “Light Pollution Is a Driver of Insect Declines”.
The article notes that sudden drops in insect numbers around the world have happened over the past couple of decades in what amounts to an insect destruction. The blame is usually assigned to “habitat loss, chemical pollution, invasive species, and climate change”. But the authors argue that the forces of lightness have not gotten their due.
A longtime preference among ecologists for studying daytime phenomena, and a preference for sleeping at night has led insect conservationists to overlook another widespread habitat disturbance, pollutant, and method of insect control: artificial light at night(ALAN).
ALAN’s influence occurs through its interference with the development, movement, foraging, and reproductive success of diverse insect species. Another factor is light’s positive effect on insectivore predation. That is, birds, bats, amphibians and arachnids aren’t stupid-if a lot of insects start swirling around lights in the night, predators will also show up.
Sadly, ALAN increases sharply after Thanksgiving, as many people add festive illumination(照明) to the exterior of their houses to celebrate the approach of Christmas. Many neighborhoods have a particular house that embraces the spirit of the season in such an outsized way as to produce a radiant haze perhaps visible to hunters in other star systems.
The task then must be to lessen the ecological consequences of ALAN on insects while still maintaining sufficient levels of nighttime illumination for human safety and enjoyment.
“Monochromatic LEDs can be engineered to produce light of any desired spectral composition,” the investigators write. “Therefore, once we know the specific wavelength affinities of insects, we can in theory design lights with minimal output in the wavelengths that most affect insect fitness.”
Turning some of the lights off might also help. In many cases, it is far easier, quicker, and cheaper to block, dim, or turn off a light source than it is to find the particular bulb type or narrow bandpass filter(滤波器) that makes its emissions visible to humans alone. Help end the war on insects. It is better to blow out one candle than to curse the planet.
1. We can know from Paragraph 2 that ________.A.lights are to blame for insect decrease |
B.lightness hasn’t got the attention it deserves |
C.lightness hasn’t caused environmental problems |
D.the dying out of insects is too slow to be noticed |
A.Most insects enjoy the lights at night. |
B.Birds and bats cannot hunt without light. |
C.Lights in the night make insects easily caught. |
D.Lights in the night has positive effect on insects. |
A.To make lights only visible to human. |
B.To use candles instead of light bulbs at night. |
C.To reduce light resource by turning off some lights. |
D.To change the light bulbs into ones with special light. |
A.The importance of light to insects |
B.The main causes of insects’ decrease |
C.To light, or to candle, that is the question |
D.Too much illumination is killing vital insects |
【推荐3】Greenhouse gas emissions would rise if all farms in England and Wales went organic. Though the emissions of each farm would go down, much more food would have to be imported, as the amount they would produce would decrease greatly.
“The key message from my perspective is that you can't really have your cake and eat it,” says Laurence Smith, now at the Royal Agricultural University in the UK, who was part of the team that ran the numbers. Smith is a supporter of organic farming and says “there are a lot of advantages of the organic approach”, but his analysis shows that organic farming has downsides too.
Farming and changes in land use, such as cutting down forests, are responsible for a third of all greenhouse gas emissions. That means reducing farming emissions and the land needed for farming is required to limit further global warming.
Smith and his colleagues found that emissions per unit of food are, on average, 20 per cent lower for organic crops and 4 per cent lower for organic animal products. However, organic harvests per hectare (公顷) are also lower on average. For wheat and barley, for instance, harvests are just half of those of traditional farms. This means 1.5 times as much land would be needed to grow the same amount of these foods.
The estimated increase in emissions varies greatly, depending on where the extra farmland comes from. If only half comes from turning grassland into farms, the increase could be as low as 20 per cent. If grassland that would otherwise have been reforested is turned into farmland, emissions could nearly double.
This doesn't necessarily mean people should stop eating organic produce, says Smith. People might choose organic food for other reasons, such as to reduce their pesticide exposure (though contrary to popular belief, organic farmers do use pesticides) or for the sake of wildlife.
Smith says the best choice may be to use some organic and traditional farming methods at the same time.
1. Why may greenhouse gas emissions increase if a country goes organic?A.Organic farms take longer to build. |
B.The agricultural output will increase greatly. |
C.The emissions of each farm unit will increase. |
D.Greater demand for imported food will be created. |
A.Changes. | B.Challenges. | C.Disadvantages. | D.Differences. |
A.Organic harvests per unit are greater than traditional harvests. |
B.Organic farming needs more farmland to feed a country. |
C.Global warming could be brought under control. |
D.Land was not used in a responsible way. |
A.Stopping using pesticides. |
B.Eating less organic produce. |
C.Going back to traditional farming. |
D.Adopting mixed farming methods. |
【推荐1】Researchers concerned with space exploration say they have discovered new evidence that Mars once had a large northern ocean. The discovery adds to existing evidence that the ancient Mars had the right conditions to possibly support some form of life.
Today, any water on Mars is believed to be in the form of ice because of the planet’s extremely cold desert temperatures. But there is a rich amount of evidence suggesting that rivers, lakes and even oceans once existed on Mars. A study by the American space agency NASA suggested that about 4.3 billion years ago, Mars likely had an ocean that covered nearly half of Mars’ northern hemisphere(半球). Another NASA-supported study guessed that about 3 billion years ago, the climate in much of the planet’s northern hemisphere was very similar to today’s Earth. The study noted that at that time, Mars likely had a much thicker atmosphere than today and had an active northern ocean.
Two American researchers recently released a set of maps to provide new environmental evidence of a large ancient ocean on Mars’ low-lying northern hemisphere. The team collected data from satellite images and photos of Mars. They then combined them to create maps of the planet’s northern hemisphere. Using the maps, the researchers were able to piece together evidence of shorelines that sat at the edge of a huge body of water about 3.5 billion years ago.
The researchers published their findings in the Journal of Geophysical Research: Planets. Benjamin Cardenas, an assistant professor at The Penn State University, was a co- writer of the study. He said the study’s findings showed the possible ocean in that area of Mars was changeable and interesting. “It was dynamic ( 动 态 的 ) . The sea level rose significantly, ” he said. “Rocks were being deposited (沉积) along its basins at a fast rate. There was a lot of change happening here. ”Besides, Cardenas suggested the new study also provided useful information on Mars’ ancient climate and developmental history. “Based on these findings, we know there had to have been a period when it was warm enough and the atmosphere was thick enough to support this much liquid water at one time, ” he said.
1. How does the author develop paragraph 2?A.By drawing comparisons. | B.By giving examples. |
C.By listing figures. | D.By asking questions. |
A.How they found the evidence. |
B.Where they created maps. |
C.Why they studied satellites. |
D.When they landed on Mars. |
A.It must have been always warm. |
B.It might have had an active ocean. |
C.The climate and sea level were unchangeable. |
D.The atmosphere was too thin to support water. |
A.Science. | B.Photography. | C.Literature. | D.Farming. |
【推荐2】Bacteria are a troublesome problem for astronauts. The microorganisms(微生物)from our bodies grow uncontrollably on surfaces(表面)of the International Space Station, so astronauts spend hours cleaning them up each week. How is NASA solving this very tiny big problem? It’s turning to a group of high school kids. But not just any kids. It’s depending on NASA HUNCH high school class, like the one science teachers Gene Gordon and Donna Himmelberg lead at Fairport High School in Fairport, New York.
HUNCH is designed to connect high school classrooms with NASA engineers. For the past two years, Gordon’s students have been studying ways to kill bacteria in zero gravity, and they think they`re close to a solution. “We don`t give the students any breaks. They have to do it just like NASA engineers,” says Florence Gold, a project manager. “There are no tests,” Gordon says.
“There is no graded homework. There almost are no grades, other than ‘Are you working towards your goal?’ Basically, it’s ‘I’ve got to produce this product and then, at the end of year, present it to NASA.’ Engineers come and really do an in-person review, and… it’s not a very nice thing at time. It’s a hard business review of your product.”
Gordon says the HUNCH program has an influence on college admissions(录取)and practical life skills. “These kids are so absorbed in their studies that I just sit back. I don’t teach.” And that troublesome bacteria? Gordon says his students are emailing daily with NASA engineers about the problem, readying a workable solution to test in space.
1. What do we know about the bacteria in the International Space Station?A.They appear in different forms. | B.They lead to air pollution. |
C.They are hard to get rid of. | D.They damage the instruments. |
A.To strengthen teacher-student relationships. |
B.To develop students’ communication skills. |
C.To allow students to experience zero gravity. |
D.To link space technology with school education. |
A.Check their product. | B.Guide project designs. |
C.Balance work schedules. | D.Grade their homework. |
A.NASA: The Home of Astronauts. | B.Space: The Final Homework Frontier. |
C.Nature: An Outdoor Classroom. | D.HUNCH: A College Admission Improvement. |
【推荐3】SHOULD WE FIGHT NEW TECHNOLOGY?
This morning, I saw the shocking headline:“Passenger Dies When Car Crashes in Driverless Mode”.In the article, various people said that the public should oppose the idea of developing driverless cars. They said that some advances in technology were unnecessary and could even be dangerous. Hence,we should cease accepting technology just because it is new. The newspaper reported that the car company had already apologised for the accident, but the families of the deceased said it was not enough. Nevertheless, the company still claimed that most people would be travelling in driverless cars one day soon.
On the one hand,there are many different groups of people around the world who live happily in the absence of new technology. Probably the most wellknown are the Amish, a group of Christians living in rural America. They do not own or drive cars, watch TV, or use the Internet. They have lived mainly as farmers since the 18th century, and they will probably be living the same way in the distant future. They advocate a simple life with an emphasis on hard work, family, and community. They think that is better than caring about luxuries or following the lives of the rich and famous. It could even be argued that the Amish's quality of life is better since they live in and appreciate the natural environment rather than living in large, polluted cities.
On the other hand, new technology has provided people everywhere with many benefits over the years. For example, the latest weathertracking computer programmes give people lots of warnings about potential natural disasters, which saves many lives. Moreover, the Internet has made it possible for friends and family to keep in touch easily even if they are on opposite sides of the world. It has also made finding opportunities in life much easier, as it allows people to make larger networks of friends through using social media.
Personally,I have benefited quite a lot from technological advances. I found my career as an AI designer through a social media network. My health monitor, which I wear all the time, has also helped me get into the best shape of my life. Of course, when new technology changes the way we live, it can be a scary prospect. Nevertheless,I will always look on the positive side of change and accept it rather than resist it.
1. Why did many people oppose driverless cars?A.Because they think new technology is unnecessary. |
B.Because they think driverless mode is dangerous. |
C.Because they are the families of the deceased. |
D.Because the company didn't apologise for the accident. |
A.They live happily in the absence of new technology. |
B.They would like to live in large and polluted cities. |
C.They are proud of owning cars and using the Internet. |
D.They want to follow the lives of the rich and famous. |
A.He feels sorry for the accident. |
B.He is opposed to new technology. |
C.He cares nothing about new technology. |
D.He is in favour of new technology. |
A.By using examples. |
B.By doing experiments. |
C.By using exact figures. |
D.By conducting surveys. |
【推荐1】Dolphins appear to make a tasty meal for many predators (捕食性动物). And why? With an exceptionally high fat content, dolphins provide great nutrition for predators who track throughout the ocean. However, dolphins are more troublesome than it’s worth and most predators generally learn to avoid dolphin groups, including sharks. Like elephants, dolphins will circle protectively around the weak members of the group, and attack anything that approaches in a threatening manner. And they can kill sharks. Most predators take one look, and then just swim away.
Dolphins don’t worry a lot about being eaten. In general, their only real predator is the shark, and even then only the larger species of sharks dare to attack dolphins. Dolphins have evolved (进化) over a long time to be pretty tough, so in general even the most dangerous sharks stay away from them. Dolphin parts have been found in the bellies of killer whales, who will eat just about anything. In fact, dolphins and killer whales team up sometimes to catch some prey.
As with most edible (可以食用的) species today, the most dangerous threat is man. Sometimes, dolphins are killed not because they are a source of food, but because they prey on the same fish species as humans. Therefore, many fishermen have killed dolphins specifically because they think dolphins will ruin their catch.
Even more, there are some countries that eat cetaceans, including dolphins. In Japan, the meat of some dolphin species is seen as a delicacy, and can cost up to $25 a pound. In Peru and many other Latin American countries where the ocean has been largely short of fish due to overfishing or environmental conditions such as El Niño, fishermen have turned to catch dolphins and porpoises to sell in fish markets.
1. What can we learn from the first paragraph?A.No ocean animals can attack dolphins. | B.Dolphins are not easy to deal with. |
C.Dolphins often kill sharks. | D.Dolphins are quite low in fat. |
A.People have ever found the evidence of killer whales eating dolphins. |
B.Dolphins and killer whales have something in common concerning bellies. |
C.Dolphins and killer whales join hands to hunt and feed. |
D.Dolphins and killer whales are not similar in belly parts. |
A.The number of dolphins is too large. |
B.Dolphins are more delicious than other species. |
C.Dolphins compete with humans on the same fish species. |
D.Dolphins’ meat is the main economic source for some fishermen. |
A.Dolphins cause overfishing. |
B.Dolphins affect their way of living. |
C.Dolphins are a source of delicious food. |
D.There are not so many fish in the ocean as before. |
【推荐2】Often we take for granted the many household items we use every day. It is difficult to imagine there was a time in the past when these inventions did not exist. Actually, several of the most common inventions have been with us for quite some time. Inventions like toothbrush, contact lenses(隐形眼镜), and credit cards came into use long ago.
The first toothbrush was introduced in China in the late 1400s but it was only 300 years later that this simple tool came into common use in Europe. By the nineteenth century, a variety of paste and powder cleaners were available throughout Europe as dental(牙齿的) care became more widespread. The first tube of toothpaste hit the market in Great Britain in 1891.
There is evidence to show that the first contact lenses were actually suggested by an astronomer, Sir John Herschel, in 1827. However, SirJohn Herschel was never able to create a working model of his idea. It was not until 1887 that a Swiss doctor from Zurich, Dr. Eugen Frick, came up with a workable process for producing precision (精密)lenses. Dr. Frick designed a new method for producing contact lenses,and the Zeiss factory in Germany began to produce contact lenses.
Credit cards have also been available for many years. They have been in use in the United States since the 1920s. At first, these cards were only used to buy gas in the quickly growing automobile service industry. Then, in the 1950s, Diners Club introduced the first general-purpose credit card. Today, credit cards such as Master Card, Visa, and American Express are commonly used by travelers around the world.
While it may be true that some of the greatest inventions and discoveries in history came about by chance, the majority of inventions that simplify our lives today came about through careful research and patient study. Of course, it still holds true that even with all the comforts of modern technology, inventors continue to search for ways of helping all of us get out of doing those necessary but tedious (乏味的) tasks which we still face. As the old saying goes, “Necessity is the mother of invention.”
1. From the second paragraph we can learn that _____.A.toothbrushes came into common use in Europe in the 17th century |
B.people could enjoy a variety of paste and powder cleaners in the 18th century |
C.more and more people paid attention to dental care throughout Europe in the 19th century |
D.the English could use different kinds of tubes of toothpaste in the early 19th century |
A.Diners Club | B.Sir John Herschel |
C.Dr Eugen Frick | D.the Zeiss factory |
A.Credit cards have a history of about two hundred years. |
B.Three kinds of credit cards are being used in the USA. |
C.The use of credit cards is closely related to the economic development. |
D.American Express is only used by American travelers now. |
A.the greatest inventions came about by chance |
B.inventions came about through careful research and patient study |
C.inventors still continue to make inventions |
D.necessity is the mother of invention |
【推荐3】The “24 solar terms” (节气) originated and was first used in China. It was created thousands of years ago on the basis of practical needs of agricultural. Ancient Chinese people used it to guide agricultural production, explain special climate signs and even come up with healthy living tips. Last year, the 24 solar terms was added to UNESCO's world cultural heritage list(联合国教科文组织世界文化遗产名录). Now, it has been brought to life thanks to a creative designer from Southwest China's Guizhou Province.
On the eve of this year's Qingming Festival, Shi Changhong released (发布) his version of reproduced and packaged characters for each solar term in the form of “moving art” of gifs. Since their first release on Zcool on March 29, the gifs have won great praise among the general public and quickly flooded the social media with millions of hits during the festival period.
To maximize publicity, Shi released his work in three forms: the video, the animation and pictures. The background sounds add to the brilliance.
“When I watch the short video, I can strongly feel the Chinese-style elements hidden in it. And it is really cool to liven up traditional Chinese culture in such a unique way.” WeChat user Xiao Feifei said.
“It is really a comfort to me to see so many people like my latest work. To be honest, it would really surprise me if the work had not aroused great interest among Chinese people. The 24 solar terms is a deeply rooted concept that covers the essence of Chinese wisdom. However, only a small portion of people know all the names or the correct order of those terms. My intention is to increase Chinese people’s self-awareness to learn more about our traditional fine culture. Actually, the 24 solar terms work is only a part of my whole design program ‘Charm China’, which I started a year ago.” Shi told China Daily.
1. Which part of the newspaper does the text probably belong to?A.Travel. | B.Culture. | C.Agriculture. | D.Education. |
A.Newspaper. | B.Magazine. |
C.Radio broadcast. | D.Website. |
A.The background sounds of the work make the video more attractive. |
B.It really surprised Shi Changhong to see so many people like his latest work. |
C.Most people know all the names or the correct order of the 24 solar terms. |
D.The 24 solar terms work designed by Shi Changhong was added to UNESCO’s heritage list. |
A.To introduce a creative designer. |
B.To introduce the 24 solar terms work. |
C.To introduce the origin of the 24 solar terms. |
D.To introduce a design program “Charm China”. |