If you have always suspected that you might just be a mosquito magnet (招蚊子的人)，scientists now have evidence for you: Mosquitoes indeed are attracted to certain humans more than others, according to a new study.
A research team at Rockefeller University sought to identify why certain people seem to draw more mosquitoes than others. Over the course of three years, researchers asked a group of 64 volunteers to wear nylon stockings on their arms for six hours a day over multiple days. Maria Elena De Obaldia, the study’s first author, constructed a glass container in which researchers put two of the stockings. The study team then released yellow fever mosquitoes into the container and observed which stocking drew more insects.
This test allowed researchers to separate study participants into mosquito magnets, whose stockings drew lots of mosquitoes, and low at tractors, who didn’t seem attractive to the insects. The scientists examined carefully the skin of the mosquito magnets and found 50 molecular compounds (分子化合物) that were higher in these participants than the others.
“We didn’t hold certain expectations about what we would find,” said Vosshall, one of the researchers. But one difference was particularly distinctive: The mosquito magnets had much higher rates of carboxylic acid (羧酸) on their skin than the low at tractors. Carboxylic acids are found in sebum, the oily substance that creates a barrier and helps protect our skin.
“The carboxylic acids are large molecules,” Vosshall explained. “They’re not that smelly by themselves,” she said. But beneficial bacteria on the skin chew on these acids that produce the characteristic smell of humans, which may be what attracts mosquitoes, according to Vosshall.
Carboxylic acids are just one piece of the puzzle in explaining how the annoying insects might choose their targets. Body heat and the carbon dioxide we release when we breathe also attract mosquitoes to humans.
Scientists still don’t know why carboxylic acids seem to attract mosquitoes so strongly. The next step might be to explore the effects of reducing carboxylic acids on the skin.
1. Why did the researchers carry out the test in the container?| A．To free people from mosquitoes. | B．To identify mosquito magnets. |
| C．To distinguish certain mosquitoes. | D．To better attract other insects. |
| A．The feature of human skin. | B．The definition of acid. |
| C．The expectation of the researchers. | D．The finding of the study. |
| A．Beneficial bacteria. | B．Body heat. |
| C．Carbon dioxide. | D．Human sweat. |
| A．They never wear stockings in summer. | B．They feature higher body temperature. |
| C．Their root cause has remained unclear. | D．Their daily routine differs from others’. |
相似题推荐
【推荐1】A herd of wild Asian elephants shot to worldwide fame while trekking (跋涉) nearly 500km from their habitat in a nature reserve, south of Yunnan province, near the borders with Myanmar and Laos.
China's official news agency, Xinhua reports that there are three calves in the herd. The giant beasts are heading north to the outskirts of the provincial capital, Kunming. They have travelled along highways and through fields of crops over the past few months. A Chinese TV station said that the animals guzzled (暴饮) down the water in a water tank of the village and feasted on kilos of corn in farmers’fields.
In recent years, with fewer herbs (草本植物) for the elephants to eat in the reserve , the creatures have been seen feeding on farmland more frequently.
It is unclear why the animals have migrated so far away from their original habitat. One reason could be a decline in the amount of edible plants in their reserve. Naturally growing supplies of the elephants’favorite foods, such as plume grass, have fallen. Another factor could be a rise in elephant numbers with around 300 up from 193 in the 1980s. A further explanation offered is that the leader elephant could have simply led a wrong way...
To reduce encounters between humans and wild animals, the local authorities developed an app that allows users to identify, locate and track wild elephants
With one click on the app, users can view the location of nearby elephants and make preparations should the animals approach. Work on the district's wild elephant monitoring and early warning system began in November,2019 ,said Tao Qing, director at Xishuangbanna National Nature Reserve
The system has greatly improved the capacity and efficiency of the local response to human elephant conflicts. Moreover , it helps provide an effective scientific basis for better protection and anagement measures and supplies reliable, timely, accurate and complete information support f decision-makers.
1. What do the wild elephants frequently enter villages for?| A．Food. | B．Research. | C．Pleasure. | D．Habitat. |
| A．To count up the exact number of elephants in the wild. |
| B．To reduce conflicts between humans and wild elephants. |
| C．To make preparations for the approach of wild elephants. |
| D．To provide timely images of wild elephants in the wild. |
| A．Costly. | B．Demanding. | C．Efficient. | D．Complicated. |
| A．Human Tracking. | B．Warning signs. |
| C．WeChat Moments. | D．High-tech monitoring. |
【推荐2】It is not easy to excite New Yorkers. This is one reason why actors and other famous people move to the city. They can live quieter lives and escape the paparazzi(狗仔队)photographers who would follow then in Hollywood.
But New York has a new media star. And this star is not living so quietly.
The star is a colorful Mandarin duck. The bird first appeared this month in a small body of water in Manhattan's Central Park.
Large crowds have gathered to see the duck. Reporters have been following its every move. The media attention on the duck has earned the name "quackarazzi"-a word combination of paparazzi and the sound a duck makes!
The duck has chosen to live in a costly pan of New York-just off Fifth Avenue, near the historic Plaza Hotel. There, hundreds of people turn up every day, hoping to see the bird show off its extremely colorful feathers.
Many people like the duck because its colors are like "sunsets," says New Yorker Joe Amato. He comes to the park nearly every day with his camera equipment.
Bird expert Paul Sweet heads a large collection of bird species at the New York-based American Museum of Natural History. He says there is nothing special about a Mandarin duck in Central Park. Central Park Zoo has its own Mandarin duck, he says. These ducks are often imported to the United States from Asia for use on private property.
Sometimes they escape, he said. Sweet said he believes this duck is an escapee. If it were wild, he added, traditional bird watchers-often called birders-would be "very excited." And they are not. "A lot of non-birders tend to see colorful birds as more beautiful," Sweet said. "But to me, it's no more beautiful than, say, a sparrow."
In this case, though, common New Yorkers get to decide what is beautiful. And they have clearly chosen this Mandarin duck.
1. What does paragraph 1 want to tell us?| A．Nothing can excite New Yorkers. |
| B．New Yorkers are hard to be attracted. |
| C．There are no actors or stars in New York. |
| D．Paparazzi photographers are popular in New York. |
| A．All New Yorkers. | B．Paparazzi photographers. |
| C．Reporters following the duck. | D．The bird experts. |
| A．This Mandarin duck is very special. |
| B．The birdwatchers are very excited. |
| C．The Mandarin duck got away from somewhere in U.S. |
| D．Paul Sweet believes the Mandarin duck is more beautiful than a sparrow. |
| A．Welcoming. | B．Indifferent. |
| C．Resistant. | D．Unclear. |
【推荐3】Princess Louisa Inlet, a fjord lying 60 miles from Vancouver, Canada, is a stretch of wilderness. Accessible only by boat or plane, the 6-kilometer-long area is popular with outdoor enthusiasts. Its dense forests are home to a variety of wildlife, including mountain goats, eagles, etc. Now, thanks to a crowdfunding campaign, the land will be preserved forever for future generations to enjoy.
The chain of events began in June 2019, when three neighboring privately-owned land parcels came up for sale. With several logging companies expressing interest, BC Parks Foundation knew it had to do something to save the land. Although it had “zero funds”, the nonprofit foundation agreed to acquire the land for CAN $ 3 million(US$ 2.3 million). Fortunately, the owners gave the nonprofit three months to collect the money.
After much consideration, the nonprofit decided to reach out to the general public through a crowdfunding campaign. To its surprise, money started rolling in from people worldwide. Among the donors was a class of fifth-grade students from Cambridge Elementary School in Surrey, British Columbia, who raised an impressive CAN $1,109 for the cause.
But in spite of the outpouring of support, on August 28, 2019——the day of the sale deadline, the nonprofit was still short of CAN $ 100,000. Just as the officials thought there was no chance of success, a businessman from Vancouver stepped in with the funds. He wrote, “These protected areas are our crown jewels, and I think it’s madness to consider letting them go for short-term economic gain when they always provide much more.”
“It’s just an amazing thing people have done. They together have saved the fjord,” said BC Parks Foundation CEO Andrew Day. “Hopefully we do see more of this kind of thing, in the right places at the right time.”
1. What can we say about Princess Louisa Inlet according to paragraph 1?| A．It is a wild place and not approachable. | B．It is impressive but not easily accessible. |
| C．It is likely to be at risk of being in ruins. | D．It is especially loved by indoor enthusiasts. |
| A．People’s sincere pray for the Inlet. | B．The sacrifice of logging companies. |
| C．People’s support for the campaign. | D．The permission to purchase the land. |
| A．Hopeless. | B．Cautious. | C．Annoyed. | D．Serious. |
| A．To introduce the beauty of the wilderness. | B．To stress the significance of the campaign. |
| C．To show the benefits of exploring the fjord. | D．To evaluate the value of Princess Louisa Inlet. |
【推荐1】Teenagers grow up very quickly. Since your last birthday, a lot of things have changed. Perhaps you've grown much taller than everyone else in your class.
What's normal? There's no one type of normal.
Don't feel afraid if you seem to have grown a lot in a very short time. Everyone experiences this during puberty (青春期). Most girls start puberty at 10, and boys at 11. But it can be earlier or later.
| A．Don't care too much about your looks. |
| B．Your looks are largely decided by your parents. |
| C．Or maybe you can't fit into your favourite pair of jeans. |
| D．Next time you go to the supermarket, take a look around. |
| E．It can be between 7 and 13 for girls and 9 and 15 for boys. |
| F．If you're worried about your changes, what should you do? |
| G．Kids who weigh more than their friends are still considered normal. |
【推荐2】We all know that turning off lights and buying energy-efficient appliances（电器）affects our financial bottom line. Now, according to a new study by University of Wisconsin-Madison researchers, we know that saving energy also saves lives and even more money for consumers as a consequence of cost benefits of improved health outcomes due to reduced energy consumption.
“By saving electricity, we can also save lives,” says Abel, director of the new study. “There is a range of health benefits. It’s a bonus. We find there are extra health reasons to turn off a light.”
Air pollution caused by emissions（排放物）from power plants is known to cause respiratory（呼吸道）diseases.
Abel and his colleagues used a suite of three widely used models to calculate power plant emissions, air quality and human deaths over three summer months, when energy use is high. Their findings show that a 12 percent increase in summertime energy efficiency（效率）would reduce exposure to air pollution. In short, cleaner air would save 475 human lives each year in the United States, worth an estimated $ 4 billion.
That savings translates to almost 5 cents per kilowatt hour of energy used. That is particularly significant, the UW team notes, given that electricity costs about 10 cents per kilowatt hour on average.
“We’re trying to clarify how changes in energy systems have benefits for public health,” explains Abel. “For the most part, the energy community is not focused on the human health effects of air pollution.”
“The new study helps build bridges between researchers and policymakers,” says Abel. By showing the savings and how to accurately calculate the value of lives saved and associated reduced health care costs, the UW team hopes to provide policymakers and the energy industry with a road map for assessing the human health benefits of reducing energy use. Ideally, putting a price tag on positive health outcomes related to reduced energy has a powerful influence on the existing strategies used by government and the energy industry to help consumers save energy.
1. What does the underlined part in Paragraph 1 indicate?| A．Less energy is consumed. |
| B．Health care costs are reduced. |
| C．The cost of electricity has fallen. |
| D．The living conditions are improved. |
| A．It saves money. | B．It makes air cleaner. |
| C．Lights may cause accidents. | D．Lights are harmful to health. |
| A．By checking the number of lights. |
| B．By working together with policymakers. |
| C．By calculating health benefits of saving energy. |
| D．By analyzing energy efficiency in summertime. |
| A．To find out how to reduce summertime energy consumption. |
| B．To develop a relationship with government and the energy industry. |
| C．To make consumers aware of the danger of air pollution. |
| D．To provide suggestions for government and the energy industry. |
【推荐3】It is a small step for a plant, and a giant leap for plant kind. A sprouting (发芽) cotton seed on China’s Chang’e-4 lunar lander is the first plant ever to grow in another world, indicating a new era for life in space.
Seeds, including cotton, arabidopsis (拟南芥), oilseed rape (油菜) and potato were carried to the Moon as a part of biological experiment, along with fruit fly eggs and some yeasts (酵母).
Pictures sent back by the probe show the cotton seeds sprouting on January 7, 2019, a few days after Chang’e-4 landed on the far side of the Moon.
The organisms (生物) are in a sealed can, protected from the extreme temperatures and radiation on the surface. “Understanding how to grow plants in space will help lay the foundation for human settlement on the Moon,” a scientist leading the experiment told the South China Morning Post.
The six organisms are intended to form a mini-ecosystem, with the plants making oxygen and food to sustain the fruit flies. Yeasts could process the flies’ waste and dead plants to provide another food source.
In a future human settlement, potatoes could provide food, rapeseed could be a source of oil and cotton could be used for clothing. A study in 2014 reported that plants could sprout and grow in lunar soil for 50 days without any additional nutrients (营养物). Over longer periods, human waste could help support plants’ nutritional needs.
These lunar green shoots aren’t the first plants in space. Astronauts on the International Space Station have grown crops including peas, radishes and cucumbers. They got their first bites of space-grown romaine lettuce in 2015.
The China National Space Administration eventually hopes to put humans on the Moon. “We are studying the program of sending astronauts to the Moon, but it’s still in very early stages,” a deputy director told the South China Morning Post. “We haven’t got the approval yet.”
1. When might Chang’e-4 land on the far side of the Moon?| A．On January 7, 2019. | B．On January 3, 2019. |
| C．On February 28, 2014. | D．On February 3, 2015. |
| A．It helps scientists understand the ecosystem in space. |
| B．It helps people living on the Moon feed themselves. |
| C．It helps support plants’ nutritional needs in space. |
| D．It helps set the basis for establishing settlements on the Moon. |
| A．Oxygen created by plants provides a food source. |
| B．The purpose of these organisms is to form a small ecosystem. |
| C．The yeast hardly plays a role in dealing with fruit flies’ waste. |
| D．The organisms can resist extreme heat and cold in the environment. |
| A．Living on the Moon |
| B．Flying to the Moon |
| C．Garden on Moon’s Far Side |
| D．Human Settlement on Moon’s Far Side |
Outwardly, I looked like the poster boy for success visiting from the United States．My white designer shirt and matching pants were straight from the shopping malls in Detroit, where I worked as an engineer．Inwardly, I was caught in a web of ambition and cultural disappointment．My clothes suggested wealthy, yet I could not afford the numerous requests for money or to make gifts of my belongings．Uncles and aunties who were prepared to mortgage （作贷款抵押） their homes to help me leave 10 years ago now expected me to finance cousins hoping to make the same move to the United States．
America had helped me achieve my ambition for furthering my education and professional experience．I had arrived with a high-school diploma, and after 10 years, I hold a graduate degree and have a relatively successful professional career．Every inch of progress, however, had been achieved through exhausting battles．My college education had been financed partly through working multiple minimum-wage jobs．I was fortunate to secure a job upon graduation, but adjusting to corporate culture made me pay another high price．Initially, I found myself putting in twice the effort just to keep up．Scared by a wave of layoffs, I went to graduate school part time because it was the only way I knew that afforded me an edge in job security．It was as though I had run 10 continuous marathons, one for each year abroad, and my body screamed for rest．
1. In the eyes of the young potato seller, the author seemed _____．
| A．to be a successful man |
| B．to have won a lottery |
| C．to represent American culture |
| D．to know a lot about the U．S． |
| A．he wants to exchange places with the young seller |
| B．he is sorry for his cousins still living in Africa |
| C．his American dream has come true |
| D．he is torn between the two cultures |
| A．studying graduate courses helped him adapt well to the life in the company |
| B．a graduate degree was the minimum requirement for his career |
| C．a graduate degree would give him an advantage over others in the job market |
| D．he wanted to settle permanently in the U．S |
| A．An immigrant was accepted by the society after ten years of struggle． |
| B．An African American returned home with fame and fortune． |
| C．An immigrant returned home with an exhausted heart． |
| D．A young African was climbing to the top of his career． |
【推荐2】Scientists have been conducting plenty of research aiming at changing thee deserts back to good land again. Via countless research and investigations, they are learning more and more about deserts,and have tried various methods to recover wasted deserts, including bringing water in so that people can live and grow food there. However, things don't seem to go well. The earth is becoming desert day by day, and some think that the scientists might not be able to change this severe situation in time.
So why is land becoming desert? Though it is partially related to natural changes, many scientists believe that it is human beings that should take the responsibility, Believe it or not, people make deserts.Some places on Earth don't get much rain, but they still don't become deserts. This is because some green plants are growing there. It is a pity that despite the countless efforts scientists have made to promote the importance of plants to stop land from becoming desert, many people still don't pay enough attention.
Small green plants and grass are very important to dry places, and prevent the sun from making the earth even drier. Plants don't let the wind blow the soil away, either. When a bit of rain falls, the plants hold the water. Without plants, the land can become desert more easily. If there were no green plants on Earth, the whole planet would eventually become desert.
1. Which of the following statements is true about deserts?| A．There have never been plants or animals in deserts before. |
| B．All the deserts on Earth can be turned into good land soon. |
| C．There is little water for growing food in the deserts. |
| D．Deserts are more often caused by natural changes in history. |
| A．scientists know well how to change desert into good land. |
| B．people should follow the scientists' suggestion to stop the land from becoming desert. |
| C．if scientists can bring water to desert, people can manage to live and grow food there. |
| D．human activity is the only reason why land is becoming desert. |
| A．Plants can keep dry land from becoming desert. |
| B．It is good to remove all the grass from the desert. |
| C．All places without much rain will become deserts. |
| D．It is better to grow grass than trees on dry land. |
| A．In a novel on desert exploration. | B．In an academic report on water shortages. |
| C．In a blog on desertification. | D．In a poster about environmental protection. |
【推荐3】The following classes will be taught online via Zoom. All registrations must be submitted online two days before your class starts. Registered students will receive registration instructions one day in advance.
Armchair Tour: Chicago Botanic Garden
Thursday, February 23
6:30—7:30 p.m.
$19/ $24
New! Strong, unified (统一的) deign is a highlight of the Chicago Botanic Garden and sets it apart from many of other gardens. You will examine the contributions of noteworthy landscape architects and building architects to explore this well-known public garden in a new way.
From the Drawing Board to Border: Online
Tuesday, February 28
6:30—8:30 p.m.
$32/ $40
Learn how to develop a shopping list and timeline to phase the work over several seasons. You’ll receive some useful tips on staging the installation (安装) of your project, finding and purchasing plants, and working with landscape professionals.
Designing the Sunny Border: Online
Wednesday, March 8
6:30—8:30 p.m.
$32/ $40
The well-designed border wears a combination of many plant that provide three seasons of color and winter interest. Learn how to artfully combine plants with an emphasis on the use of color, and form. Whether you are a new gardener or have an established border that could use updating, this class is for you.
Designing the Shade Garden: Online
Wednesday, March 15
6:30—8:30 p.m.
$32/ $40
A garden shaded by trees or buildings is often a challenge for the gardener who is faced with low light levels, tree roots, and soil that is often dry. Discover solutions and ideas for artful plantings that can help you create effective combinations with optimal (最佳的) color, and form.
1. What must students do before the four classes?| A．Reserve the classes. | B．Hand in homework. |
| C．Read the instructions. | D．Visit the four gardens. |
| A．Combine plants with the surroundings. | B．Shade a garden with trees or buildings. |
| C．Admire great works by famous architects. | D．Learn how to make a detailed grocery list. |
| A．Chicago Botanic Garden. | B．Designing the Sunny Border. |
| C．Designing the Shade Garden. | D．From the Drawing Board to Border. |
