Have you ever wondered how mosquitoes are so good at finding you? A new study has just identified a new way they home in on us. It’s visual. Mosquitoes just like the look of our skin.
Claire Rusch and her colleagues have been working to uncover ways to avoid mosquito bites. And this biologist knows plenty about that. After all, to study mosquitoes, “you get bitten a lot,” she notes. “It’s not easy to work with an animal that preys(捕食) on you.”
To test whether a mosquito has color preference, Rusch got help from a software engineer who designed a test box that was 450 mosquito-body-lengths long. Lined with cameras, it recorded the insects’ flight patterns. Two small colored disks were laid on the floor of the box.
The researchers released about 50 starved mosquitoes into the box. Mosquitoes don’t start hunting until they’ve smelt carbon dioxide(CO2). So, the team sprayed(喷) CO2 inside the box as part of the experiment. Cameras recorded where’ the mosquitoes flew and how they interacted with the colored disks. Whichever disk the mosquitoes flew around longer would be the color the insects preferred.
They found before CO2 was sprayed, the mosquitoes ignored all the colored disks. With CO2, mosquitoes ignored any disk that was green, blue or purple. But the insects did fly toward disks that were red, orange or light blue. These colors, apparently, were inviting. The mosquitoes seemed to especially like red.
The result was beyond the researchers’ expectations because scientists long thought that mosquitoes relied mostly on body smells and heat to find humans. Now, they know that vision also plays an important role.
There is still much to learn about how mosquitoes see their world. It seems logical that mosquitoes might be attracted to red since that is the color human skin appears to them. Still unknown is why they are also attracted to light blue. And, importantly, how might these new data on color preferences be used to design better mosquito traps?
1. What does the underlined word “that” in paragraph 2 refer to?| A．identifying various mosquitoes. | B．Teaming up with other colleagues. |
| C．Avoiding being bitten by mosquitoes. | D．Uncovering ways to catch mosquitoes. |
| A．To stop mosquitoes flying away. | B．To track mosquitoes more easily. |
| C．To make mosquitoes hunt actively. | D．To put more pressure on mosquitoes. |
| A．Mosquitoes track people by smelling. | B．Mosquitoes are good at finding their targets. |
| C．Mosquitoes see the world in a different way. | D．Mosquitoes can use eyes when hunting food. |
| A．The things remaining to be explored. | B．The world in the eyes of mosquitoes. |
| C．The color preferences of mosquitoes. | D．The practical application of the findings. |
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【推荐1】Bees and butterflies are active during the daytime. They get a lot of attention for their roles as pollinators(传粉者).But moths(蛾)aren't given the prominence they deserve.
Actually, moths are seen much less often, because they're active at night. Moth bodies often seem furry. Pollen—a yellow powder in the center of most flowers, from one flower sticks to their bodies and falls off when they move to other flowers. Scientists studied insects around nine ponds on farmlands in the United Kingdom. They visited these ponds once a month from March to October.
They studied three groups of insects: moths, bees that normally work together, like honey bees, and flying insects which work alone, such as butterflies. At the ponds, the scientists caught these flying insects and died to collect pollen from their bodies. In all, the scientists checked 838 moths, 632 other insects which work alone, and 1,548 honey bees.
By studying the pollen they collected, the scientists were able to see which plants the insects had visited. The moths had pollen from 47 different kinds of plants, including seven plants that bees don't normally visit. The honey bees had pollen from 46 different kinds of plants. The other insects that work alone had visited 45 different kinds of plants. Richard Walton, who led the study, says that bees usually choose the plants with the most nectar(花蜜)and most pollen. However, moths pollinate many different plants, filling in the gaps left by the daytime pollinators.
Not only do moths pollinate plants, they also provide important food for birds and bats.
But, like many other insects, moth numbers have dropped greatly in the last 50 years, mainly because of pesticides and the loss of natural lands. Just like bees and butterflies, moths are worth protecting. "Moths are by no means less important," says Dr. Walton.
1. What does the underlined word probably mean in paragraphl?| A．Praise. | B．Chances. |
| C．Concerns. | D．Future. |
| A．Moths and other insects' living habits. |
| B．Research on insects' spreading pollen. |
| C．Classification of insects by scientists. |
| D．The ways in which moths carry pollen. |
| A．They are less choosy. | B．They eat less in the daytime. |
| C．They are more diverse. | D．They carry more pollen. |
| A．Moths Pollinate Plants Strangely |
| B．Moths Are More Vital Than We Think |
| C．Moths Help Bees to Pollinate Plants |
| D．Moths Visit Some Flowers Bees Skip |
【推荐2】According to a study published last week in the journal Science, scientists have found a way to change a plant’s genes (基因) in order to make it use sunlight more quickly. Someday, the results could increase the amount of food produced around the world.
By changing a plant’s genes, the scientists were able to increase leaf growth on plants by 14-20 percent. Specifically, scientists changed the plant’s protective (保护的) system. “Normally, this system is activated when a plant gets too much sunlight,” said scientist Krishna Niyogi, co-author of the study. “When the plant senses the light, it gets rid of extra energy and creates more leaves. When the plant is in the shade, the protective system is turned off. But the process is slow.”
Stephen Long is the lead author of the study. He compared a plant’s protective system to light-adjusting glasses. “When a person wears the glasses outside during the day, the lenses (镜片) darken and lighten depending on how sunny it is. Plants do the same thing,” he said. “But in plants the adjustment can take anywhere from 10 minutes to an hour. This makes it hard for plants to get the right amount of sunlight needed to create food.”
The new study sped up the process. By changing the plant’s genes, it’s more quickly than normal to turn on and turn off the protective system. As a result, leaf growth on the plants scientists used in the study increased. Leaf growth on two plants increased by 20 percent, while leaf growth on a third plant increased by 14 percent. Scientists conducted the study on tobacco plants. But they thought the genetic modification would produce the same results in corn or rice.
1. What does the plant’s protective system need to keep activated?| A．Mild shade. | B．Leaf growth. |
| C．Genetic changes- | D．Enough sunlight. |
| A．Because it isn’t always sunny. |
| B．Because leaf growth increases too slowly. |
| C．Because the light-adjustment process is a bit long. |
| D．Because the protective system is turned on and off more quickly. |
| A．Development. | B．Decoration. |
| C．Change. | D．Copying. |
| A．Changing how a plant uses sunlight could mean more food in the future . |
| B．When the plant is in the shade, its protective system is turned off slowly. |
| C．Too much sunlight will damage plants’ protective system. |
| D．It is hard for plants to create food without enough sunlight. |
Once there was a baby eagle living in a nest (巢) on a cliff (山崖)．The baby eagle loved his nest．It was warm, soft and comfortable．And even better, he had all the food and love that his mother could give．Whenever the baby eagle was hungry, his mother would always come just in time with the delicious food he liked.
He was growing happily day after day．But suddenly his world eagle changed．His mother stopped coming to the nest, he was full of sadness and fear．He thought he would die soon．He cried, but nobody heard him.
Two days later mother appeared with some nice food．The baby eagle was wild with joy．But his mother put the food at the top of the mountain and then looked down at her baby．
The baby eagle cried out, “Mum, why did you do this to me? I’m hungry．Don’t you know I will die if I have nothing to eat?”
“Here is the Last meal I give you．Come and get it by yourself.” his mother said．Then she flew down and pushed the baby eagle out of the nest.
The baby eagle fell down, faster and faster．He looked up at his mum.“ Why do you abandon me?” He looked down at the earth．The ground was much closer．Then something strange happened．The air caught behind his arms and he began to fly! He wasn’t moving to the ground any more．Instead, his eyes were pointed up at the sun.
You are flying! You can make it!” His mother smiled.
1. Which of the following is TRIJE about the baby eagle’s life before his mother stopped coming to the nest?
| A．lie lived in a nest in the tree． |
| B．He was always cold and hungry． |
| C．He lived very happily with friends． |
| D．His mother offered him nice food. |
| A．Sad |
| B．Afraid |
| C．Happy |
| D．Angry |
| A．保护 |
| B．抛弃 |
| C．歧视 |
| D．拯救 |
| A．The baby eagle lost his mother |
| B．The baby eagle fell down and died |
| C．The baby eagle was still angry with his mother. |
| D．The baby eagle could get food himself. |
【推荐1】The Amazon Rainforest: A Natural Treasure
Welcome to the Amazon rainforest. As the largest rainforest in the world, it plays a significant role in maintaining the fine balance of the Earth’s ecosystem.
The Amazon rainforest crosses into eight countries. With an area of 5.5 million square kilometers, the Amazon rainforest is more than half the size of China. The Amazon River, from which the rainforest gets its name, is about 6,400 kilometers in length. On its journey from the mountains to the ocean, the river supports many different ecosystems.
The forest’s different levels support an unbelievable variety of wildlife. At the bottom, there is a system of roots beneath the ground. Above that is the mass of leaf litter on the dark forest floor.
More than 1,300 species of birds and over 400 species of mammals hide among the jungle’s plant life. The jaguar(美洲豹) is one example. It has yellowish-brown coat with black spots. While a significant number of jaguars survive here, they are only one element of this forest’s food chain.
The Amazon rainforest breathes life into the planet by absorbing carbon dioxide and producing over 20 percent of all the Earth’s oxygen.
| A．They feed on many species, including frogs. |
| B．Thus, it’s often known as the “lungs of the planet”. |
| C．Rivers tend to be the easiest way to enter the forest. |
| D．The next level is made up of shorter plants with large leaves. |
| E．They give this area the richest species of plants and animals on the Earth. |
| F．Currently the trees in the Amazon rainforest absorb around 500 billion tonnes of carbon dioxide each year. |
| G．Over the past 50 years, 17 percent of the rainforest has disappeared due to human activities. |
【推荐2】Underwater travel is difficult and dangerous, but many people have to stay deep under the ocean. Thus, humans have come up with a few designs of vehicles to move around under the ocean. But what if there was a better way to travel?
Hilary Bart-Smith, an engineer at the University of Virginia, thinks a vehicle that travels like a manta ray (魔鬼鱼) would be able to operate for long periods at sea. Manta rays which can grow up to 29 feet long are among the most efficient swimmers in the ocean. Different from animals and people pushing against water, manta rays swim by moving through the water with wing-like movements of their fins (鳍). Efficiency means using less energy to move farther.
Bart-Smith and other engineers at the University of Virginia had to find out what manta rays looked like on the inside to better understand how they move. They took X-rays to find out how a manta ray’s fins are built. They found that a web of cartilage (软骨) stretches across each fin.
Once the engineers knew how a manta ray’s fin was constructed, they could build one of their own. They made a long row of metal struts with many hinges to imitate the manta ray’s web of cartilage. The engineers put their design inside a flexible cover, shaped like a manta ray’s fin. Then they tested it in the university swimming pool. They were happy to see that it swam just like a manta ray in the ocean.
Engineers and scientists are still learning and experimenting with how to imitate these amazing animals. For now, engineers study their movements and learn from the most efficient swimmers in the ocean. Perhaps someday engineers will be able to build manta ray robots that are big enough to transport people.
1. How do man ta rays swim?| A．By moving like birds. | B．By swimming like humans. |
| C．By swimming like other fishes. | D．By pushing against water like animals. |
| A．Manta rays look like travel vehicles. |
| B．Manta rays are the fastest swimmers. |
| C．Manta rays can grow at least 29 feet long. |
| D．Manta rays’ fins consist of a web of cartilage. |
| A．To learn about their habits. | B．To control manta ray robots. |
| C．To protect marine creatures. | D．To design undersea vehicles. |
| A．Supportive. | B．Negative. | C．Doubtful. | D．Objective. |
【推荐3】In biology, evolution is a process by which species change over time. Evolution is a theory-an explanation about how the world works, backed by evidence. The theory of evolution states that groups of organisms change over time.
Keep in mind that groups don't evolve to become more “advanced” than their ancestors. Their ancestors did well enough to pass on their genes, after all! Species are always changing, so are their environments. Sometimes their environment might have more or less food. A new predator might appear.
Since every individual within a group is different, some usually have features that help them survive the change.
There's also plenty of evidence that evolution is taking place now. For example, as the climate changes, a kind of owl populations are becoming more brown than gray. There is less snow cover that might make a brown owl stand out, but browner owls hide better in brown trees. Some scientists also use the word evolution to refer to a series of changes in the non-living world. The shape of mountains might evolve as time wears them down and rocks below push them up.
| A．That's quite true. |
| B．The climate might change. |
| C．The theory also explains how groups change. |
| D．Groups of living organisms will grow rapidly. |
| E．Scientists have a lot of evidence that evolution occurs. |
| F．These individuals will be more likely to survive and reproduce. |
| G．A computer chip might develop as new innovations help it work faster. |
【推荐1】Twelve wants to make a great number of products greener by changing where the carbon used in their production comes from — taking it from carbon dioxide caught in the air instead of from the ground in the form of fossil fuels. “If we can take the basic carbon molecule (分子) and put new elements around it, in that case, it can be useful in industry,” says co-founder Etosha Cave, “we can basically shift what’s happening with our atmosphere and what’s happening with climate change.” Or, as her fellow co-founder Kendra Kuhl puts it: “Changing carbon changes everything.”
To achieve this transformation (转变), the company created a catalyst, something that breaks down carbon dioxide caught from the air into smaller atomic bits, such as carbon and oxygen, using water and electricity to recombine the elements and for mother carbon compounds (混合物) that make up the basis of a wide range of chemicals and fuels.
Twelve’s carbon transformation system can be added to existing producing processes and it send products used as a direct replacement for standard petrochemicals. That allows other companies to cut their dependence on fossil fuels in production.
“By sourcing carbon from carbon dioxide instead of fossil fuels, we can largely reduce our emissions (排放) while keeping the products we know and love,” says Cave. Brands are taking note. Twelve’s chemicals are currently being used to produce Mercedes-Benz car parts, a line of Pangaia sunglasses and soon.
Twelve also created his own sustainable (可持续的) fuels, E-Jet and E-Marine, which are used to power aircraft and ships.
1. What allows Twelve to make greener products?| A．Taking carbon from the air. |
| B．Transforming the forms of fossil fuels. |
| C．Fixing the climate and atmosphere problems. |
| D．Planting more trees for new chemical elements. |
| A．Preparing water and electricity. |
| B．Collecting carbon dioxide from the air. |
| C．Separating carbon dioxide into smaller parts. |
| D．Rejoining elements like carbon and oxygen for the mixture. |
| A．Reducing the costs of their products. |
| B．Making them better known to the world. |
| C．Being less dependent on fossil fuels than ever. |
| D．Creating more sustainable fuels for other fields. |
| A．Twelve’s Great Achievements | B．Green House Effect |
| C．Carbon Transformation System | D．Limitations of Fossil Fuels |
【推荐2】Scientists have designed transparent wood that could replace conventional glass in windows.
The innovation was developed using wood from the balsa tree, which is native to South and Central America, and claims to be five times more thermally efficient than glass.
The team treated balsa wood in an oxidizing bath that bleaches it of nearly all visibility and then penetrated it with polyvinyl alcohol(PVA), creating a product that is virtually transparent.
Unlike traditional glass, the transparent wood can withstand much stronger impacts and will bend when damaged, instead of breaking into a lot of small pieces.
The transparent wood was created by teams at the University of Maryland and University of Colorado, which set out to find a greener alternative to conventional glass-a product that creates 25,000 tons in carbon emissions each year. Along with contributing to greenhouse gases, glass contributes to a loss of energy.
“Residential building windows in particular account for 10%～25%of the heat loss due to their poor thermal management capability,” the team wrote in the study. “Exploring energy efficient window materials is thus highly desirable to address heating costs, energy shortages, and the global impact of climate change associated with increased carbon emissions.”
The team notes that the bonding between PVA and cellulose in the wood, creates a tightly packed structure that allows for more thermal protection and makes it more durable and lighter than glass.
“Switching to transparent wood could prove to be efficient as well, ” researchers shared in a statement. “It is approximately five times more thermally efficient than glass, cutting energy costs. It is made from a sustainable, renewable resource with low carbon emissions. It also agrees with existing industrial processing equipment, making future mass production easier.”
1. From where can you know how the transparent wood is made?| A．Paragraph 1 | B．Paragraph 2 | C．Paragraph 3 | D．Paragraph 4 |
| A．It is environmentally-friendly. | B．Its cost is much higher than glass. |
| C．It has been made in large quantities. | D．It is designed to give off heat easily. |
| A．It is difficult for people to get used to the transparent wood. |
| B．Conventional glass in windows is likely to remain popular. |
| C．Existing industrial processing equipment is still inadequate. |
| D．The future of the transparent wood is promising. |
| A．A better way to make windows. | B．An alternative to window glass. |
| C．The transparent wood in concept. | D．A tree used for transparent wood. |
【推荐3】There has long been a view that in ancient times men were the hunters-out getting the neat — while women were gatherers-searching for fruit, vegetables and wild plants.
However, this stereotype has been overthrown by an archaeological discovery. Scientists found the remains of a teenage girl, who lived around 9,000 years ago, at a site in Peru alongside a hunting toolkit(工具箱).There was a knife and fakes(薄片)of rock for removing internal organs(内脏), and other hunting tools.
"It took a strong case to help us recognize that the archaeological pattern indicated actual female hunting behavior," said Randy Has, he lead author of the study.
The remains were recovered in 2018 when an archaeological site was being excavated(挖掘). Actually, Haas' team didn't plan to study female hunters. They found six bodies in a burial pit, a site 3,925 meters above sea level, on a windy plateau in southern Peru. The researchers used a new method to determine the sex of the found bones. The technique analyzed a protein in the remains' tooth enamel(釉质)to tell their gender. It turned out that the remains with an impressive hunting kit belong to a female.
According to the study and previous records of 107 other burial sites throughout North and South America, the team thinks that between 30 percent and 50 percent of big-game hunters who lived more than 10,000 years ago in the Americas could have been women.
However, some people think the hunting tools could have been placed there for symbolic or religious reasons, so the girl might not be a hunter.
In response, Haas pointed out the 9,00-year-old tomb contains a wide variety of tools-some are very rare, some are common — so this suggests that these tools were not some kind of sacrificial(献祭的)offering. Rather, they were the object that individuals used regularly.
Haas said this debate has great significance in today's world. "This insight-for me at least-stresses that many of the gender inequalities we see today do not have a biological basis," he said.
1. What is the word "overthrown" in paragraph 2 closest in meaning to?| A．Established. | B．Supported. |
| C．Explained. | D．Challenged. |
| A．It was aimed at learning about ancient female hunting behavior |
| B．A total of six bodies were discovered in northern Peru |
| C．A protein in the remains' tooth enamel was examined to know their gender |
| D．It suggested that most females in ancient times were hunters. |
| A．For daily uses. | B．For sacrificial offerings |
| C．For symbolic practices. | D．For religious purposes |
| A．Males should be to blame for gender inequalities. |
| B．There were fewer gender inequalities in ancient times. |
| C．Many gender inequalities are not supported by biology. |
| D．We should ignore biological differences between males and females. |
