Researchers studied a group of black-legged kittiwakes that nest in an abandoned radar tower on Middleton Island, Alaska. They attached GPS-accelerometers onto kittiwakes to track their flight performance and discovered that they sometimes travel as far as 155 miles (250 kilometers) a day to find food.
By combining data from the GPS tracker with minute muscle samples from some of the birds, the researchers found that — despite beating their wings less frequently — birds with larger muscle fibers were able to fly as fast as those with smaller fibers. The team also found that birds that flew faster had a higher number of nuclei — which produce the proteins to power flight — in their muscle cells, allowing the birds to increase more muscle fibers to power their flight.
Athletes exercise to maintain muscle tone. The same may be happening with kittiwakes, with those individuals that exercise the most — that is, fly the most — having better developed muscles than those that move less.
“Past studies have focused on hormone levels, body mass, or levels of red blood cells as a predictor of flight performance. We found that muscle structure and body mass together predict performance, says study coauthor Kyle Elliott, an assistant professor in McGill University's department of natural resource sciences in the Bieler School of Environment.
“With the data from the GPS-accelerometers, we can understand a lot about these birds, like where they're going to find food, how fast they're flying, and how frequently they're beating their wings in flight," says Kristen Lalla, the first author of the paper, which she co-wrote as an undergraduate student under Elliott's guidance. “In the past, one of the challenges of measuring muscle structure in small birds was that it usually requires dissecting (解剖)the muscle."
1. What do the first two paragraphs tell us about kittiwakes?| A．They nest in an abandoned Island of Alaska. |
| B．With smaller muscle fibers, they can fly faster. |
| C．They often travel as far as 250 kilometers a day. |
| D．Muscle fibers play an important role in their flight. |
| A．Body mass. |
| B．Hormone levels. |
| C．Levels of red blood cells. |
| D．Muscle structure and body mass. |
| A．The influential factors of kittiwakes' flight performance. |
| B．The importance of protecting kittiwakes. |
| C．The reasons for Kittiwakes flying so far. |
| D．The process of kittiwakes' flying. |
| A．Sport. | B．Nature. | C．Health. | D．Entertainment. |
相似题推荐
The earthquake affected the students of the destroyed areas in many ways:losing parents,being scared and feeling lonely.How can we help them?Teens reporter talked with Lin Dan,the program director of the Sunshine in Your Heart Project at the Red Cross Society of China.
How will the earthquake affect the teenagers mentally?
They’ll have feelings of fear,anger and feel they are not safe.They will find it hard to focus.They will tend to cry,shout and tremble.And they might be afraid to be alone.
What will happen if they are not helped?
The teenagers will find it hard to live in a balanced way.If things get worse,they might not be able to focus on their studies.They might give up on life.
How can we help them overcome these problems?
The first thing is to build up trust with them.Show your sympathy and sadness,and be their friends.Then you have to give them a sense of safety.Tell them that there’s a solution to every problem.Thirdly,try to satisfy their psychological needs. Some of us were not directly affected by the quake but have seen images on TV and feel scared.What should we do?
Talk with an adult or share your feelings with someone who might feel similar.If this doesn’t help,then you should see a doctor for professional help.
1. What’s the BEST title of the passage?
| A．The scare caused by the earthquake |
| B．Dealing with the pain left behind after the earthquake |
| C．How to get a sense of safety |
| D．The psychological needs |
| A．They’ll tend to cry,shout and tremble. |
| B．They may be afraid to be alone. |
| C．They’ll feel unsafe. |
| D．They’ll feel sympathetic. |
| A．mental | B．physical |
| C．material | D．professional |
| A．the scare caused by the earthquake can be relieved quickly |
| B．seeing a doctor is the most important measure to deal with the problems |
| C．the images on TV can also affect people and even cause problems |
| D．to help them overcome these problems,we should always talk with them |
【推荐2】Twenty minutes of exercise may help kids with ADHD(小儿多动症) settle in to read or solve a math problem, a new research suggests.
The small study, of 40 8～10 year-olds, looked only at the short-term effects of a single period time of exercise. But researchers warn that they are not saying exercise is the answer to ADHD.
But it seems that exercise may at least do no harm to kids' ability to focus, they say. And further studies should look into whether it's a good choice for managing some children's ADHD.
“This is only a first study,” said lead researcher Matthew B. Pontifex, of Michigan State University in East Lansing.
“We need to learn how long the effects last, and how exercise might combine with or compare to traditional ADHD treatments” like stimulant medications(刺激性药物), Pontifex explained.
He noted that there's been a lot of research into older adults. But little is known about kids, even though some parents, teachers and doctors have advocated exercise for helping children with ADHD.
So for their study, Pontifex and his colleagues found 20 children with diagnosed(诊断) or suspected ADHD, and 20 ADHD-free kids of the same age and family-income level.
All of the children took a standard test of their ability to ignore distractions(注意力分散) and stay focused on a simple task at hand - the main ability” that troubles kids with ADHD, Pontifex noted. The kids also took standard tests of reading, spelling and math skills.
Each child took the tests after either 20 minutes of treadmill(跑步机) exercise or 20 minutes of quiet reading (on separate days). Overall, the study found, both groups of children performed better after exercise than after reading.
On the test of focusing ability, the ADHD group was correct on about 80 percent of responses after reading, versus(相对于) about 84 percent after exercise. Kids without ADHD performed better -reaching about a 90 percent correct rate after exercise.
Similarly, both groups of kids scored higher on their reading and math tests after exercise, versus post-reading.
1. What does the new research suggest?| A．Exercising will make kids with ADHD stronger. |
| B．Exercising will help kids with ADHD focus better. |
| C．Exercising will help make math problems easier. |
| D．Exercising will help kids read more quickly. |
| A．There is too much research into the older adults. |
| B．The research about the ADHD is enough. |
| C．The research about kids with ADHD is limited. |
| D．Exercise is not combined with traditional treatment. |
| A．They need to compare their performance with that of kids with ADHD. |
| B．They need them to do some reading and math problems after school. |
| C．They need them to take a standard test of their ability to ignore distractions. |
| D．They need them to take standard tests of reading, spelling and math skills. |
| A．Kids with ADHD performed better than kids without ADHD in reading. |
| B．Kids without ADHD performed the same before and after exercising. |
| C．Both groups scored higher on their reading and math tests after reading. |
| D．Both kids with ADHD and without ADHD performed better after exercise. |
【推荐3】The people who happen to be in a city center at any given moment may seem like a random collection of individuals. But new research featuring a simple mathematical law shows that urban travel patterns worldwide are, in fact, predictable despite location.
Researchers discovered what is known as an inverse square relation (平方反比关系) between the number of people in a given urban location and the distance they traveled to get there, as well as how frequently they made the trip. It may seem intuitive (直觉的) that people visit nearby locations frequently and distant ones less so, but the newly discovered relation accurately predicts, for instance, that the number of people coming from two kilometers away five times per week will be the same as the number coming from five kilometers twice a week.
The researchers analyzed data from about eight million people between 2006 and 2013 in six urban locations. This study focused on locations and examined how many people were visiting, from how far and how frequently. The researchers found that all the unique choices people make—from dropping kids at school to shopping-obey this inverse square law.
One explanation for this strong statistical patter is that traveling requires time and energy, and people have limited resources for it. At the core is the effort that people are willing to invest collectively to travel to certain locations, trying to optimize their days.
Understanding these patterns is important not only for planning the placement of new shopping centers or public transportation but also for modeling disease transmission within cities, says Kathleen Stewart, a geographer and mobility researcher.
Many researchers estimate travel with “gravity models”, which assume that movement between cities is proportional (成比例的) to their population sizes. But these models do not account for travel patters within cites—information that is particularly critical in dealing with disease transmission Epidemiologist (流行病学家) Sam Scarpino says models based on this new finding might better track that flow.
“Those organizational patterns have really profound (深远的) implications on how COVID will spread,” Scarpino says. In a smaller rural location, where many people regularly go to the same grocery store, the entire town will experience sharp peaks of infections as the virus sweeps through the community. But in a bigger city, the spread takes longer he explains, because mini epidemics can occur in each neighborhood somewhat separately.
1. What does the underlined word “optimize” in Paragraph 4 probably mean?| A．Slow down. | B．Keep a record of. |
| C．Think back on. | D．Make the most of. |
| A．To introduce the travel patterns within cities. |
| B．To stress the importance of tracking diseases. |
| C．To compare the urban and rural infection rates. |
| D．To show the advantage of the inverse square law. |
| A．Diseases spread faster in rural areas than big cities. |
| B．Trip distance seldom influences people’s travel choices. |
| C．Epidemics are harder to discover in big cities than in rural areas, |
| D．City residents are likely to make frequent trips to a distant place. |
【推荐1】Fish farming is the fastest-growing form of food production worldwide. Seafood accounts for around 17% of the world’s protein intake. It’s estimated that global consumption of fish will reach 180m tonnes by the end of the decade. The World Bank thinks that 90% of the world’s fisheries are being fished over their capacity. Aquaculture (水产养殖) has therefore accounted for nearly all the growth in fish consumption since 1990. It’ll account for almost all the growth to come, too.
As with farming on land though, aquaculture has some problems. Many farmed fish are grown in net pens (网栏) either in rivers or the open ocean. Uneaten food and fish waste can pollute surrounding waters. When net pens break, escaped farmed fish can damage the local ecosystem. Inland “flow-through” farms require continuous streams of fresh water from rivers, competing with those who might need to drink it.
Therefore, newer fish farms, like Salten Smolt, came into being. They adopt a technology called RAS (recirculating aquaculture systems). Rather than relying on a constant flow of water to keep fish healthy, a RAS farm grows fish on land in tanks whose water is continuously cleaned and recycled. Standard salmon farming consumes about 50,000 litres of water for each kilogram of salmon produced. A RAS farm might need just 150 litres. Besides, it takes better care of the fish, and allows picky species to be raised anywhere. However, the pipes, pumps and monitoring systems mean that costs are higher. And these systems need to be monitored regularly by skilled personnel in case of a loss.
The RAS tanks are climate-controlled tanks, which can provide ideal temperature, without the need to worry about terrible weather. Reel Data, a company in Nova Scotia, uses data from cameras and sensors in tanks to estimate how hungry fish are, how much they weigh and even how stressed they are. The firm says the technology can raise its productivity by up to 20%.
For now, the RAS farm remains small fry (鱼苗). Just as Kathrin Steinberg, head of research at the Aquaculture Stewardship Council, said, less than 5% of the farms certified by her organization make use of it. But with the world’s demand for fish rising rapidly, she believes that market share will definitely grow soon.
1. What does the author highlight in Paragraph 1?| A．The benefit of consuming seafood. | B．The rapid development of fisheries. |
| C．The difficulty of increasing food production. | D．The significance of developing aquaculture. |
| A．They may bring about a waste of land. | B．They may lead to declined fish diversity. |
| C．They may cause environmental concerns. | D．They may struggle to meet local demand. |
①expense-saving ②water efficient ③flexible site selection ④fewer disease outbreaks
⑤highly productive ⑥complete auto-monitoring system
| A．①②④⑤ | B．②④⑤⑥ | C．①③④⑥ | D．②③④⑤ |
| A．The future of fish farming is on land | B．We will have more choices for our dinner |
| C．The global seafood consumption is on the rise | D．We will witness a great reform in food production |
【推荐2】AIDS may be one of the most undesirable diseases in the world. Luckily, there is now hope for AIDS patients. According to a recent paper published in the New England Journal of Medicine, Chinese scientists have successfully used CRISPR technology-a method of gene editing-to treat a patient with HIV. While it may not have cured the patient fully, it still represents a huge step forward in fighting the disease.
The patient was a 27-year-old Chinese man who was diagnosed with both AIDS and acute lymphoblastic leukemia, a type of blood cancer. Despite his bleak situation, doctors offered him a glimmer of hope: a bone marrow (骨髓) transplant to treat his cancer and an experimental treatment for his HIV.
They edited the DNA in bone marrow stem cells from a donor before transplanting the cells into the patient. Specifically, the treatment involved using the gene-editing tool CRISPR-Cas9 to delete a gene known as CCRS, which encodes a protein that HIV uses to get inside human cells. Without the gene, HIV is unable to enter cells. Talking about the gene, lead scientist Deng Hongkui told CNN, “After being edited, the cells-and the blood cells they produce-have the ability to resist HIV infection.” Nineteen months after the treatment, the patient’s leukemia was in complete relief and donor cells without CCR5 remained, according to the research paper.
Though the transplant did not cure the man’s HIV, it still showed the effectiveness of gene-editing technology, as there was no indication of any unintended genetic alterations (改变) -a major concern with past gene therapy experiments.
Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security in the United States, who was not involved in the study, praised the treatment. “They did a very innovative experiment, it was safe,” he told Live Science. “It should be viewed as a success.”
Deng believes gene-editing technology could “bring a new dawn” to blood-related diseases such as AIDS and sickle cell anemia. Thanks to this new technology, “the goal of a functional cure for AIDS is getting closer and closer,” he said.
1. How did the new treatment fight against HIV?| A．By preventing HIV from entering cells. | B．By changing the structure of HIV. |
| C．By removing a protein that HIV feeds on. | D．By identifying and killing HIV. |
| A．CCR5 and other genes in the patient’s cells were changed. |
| B．Some of the patient’s blood cells could resist HIV infection. |
| C．HIV could no longer get into the patient’s cells. |
| D．The donor cells without CCR5 disappeared finally. |
| A．It has provided an innovative way to cure AIDS patients. |
| B．It pointed out the problems of gene therapy for AIDS. |
| C．It’s the first experiment to use gene-editing technology to treat AIDS. |
| D．It could offer a safe treatment for blood-related diseases. |
【推荐3】If you do not use your arms or your legs for some time, they become weak. When you start using them again, they slowly become strong again. Everybody knows that. Yet many people do not seem to know that memory works in the same way.
When someone says that he has a good memory, he really means that he keeps his memory in practice by using it. When someone else says that his memory is poor, he really means that he does not give it enough chance to become strong.
If a friend says that his arms and legs are weak, we know that it is his own fault. But if he tells us that he has a poor memory, many of us think that his parents are to be blamed (责备), and few of us know that it is just his own fault.
Have you ever found that some people can’t read or write but usually they have better memories? This is because they cannot read or write and they have to remember things; they cannot write them down in a little notebook. They have to remember days, names, songs and stories; so their memory is the whole time being exercised. So if you want to have a good memory, learn from the people: practice remembering.
1. Which of the following is right?| A．Your arms or your legs will become weak when you use them. |
| B．Your memory works in the same way as your arms and legs. |
| C．Everybody knows that memory works in the same way as their arms and legs. |
| D．Your memory can’t become strong again when you use them again. |
| A．practice it |
| B．not give it enough chance to become strong |
| C．have clever parents |
| D．use your arms and legs often |
| A．his teachers’ fault | B．his parents’ fault |
| C．his own fault | D．his strong arms and legs |
| A．they have to remember everything | B．they can’t write them down |
| C．they practice remembering | D．they can remember things quickly |
| A．how to remember days, names and songs |
| B．a good memory needs strong arms and legs |
| C．a good memory comes from practice |
| D．parents can make us clever |
【推荐1】I have been receiving so much kindness. It was difficult for an independent girl like me to accept it at first. At times, my financial situation is not the best. But with that comes a great lesson in appreciation, budgeting, and deciding what is and what isn't important.
A few times I've had to put off or even give up things. Because of my scarcity on money, I had to give up a keep-fit exercise, which is something I like to treat myself regularly. When my coach Lisa heard about this, she offered me training at a highly discounted price. At first this made me very uncomfortable. I feared that she would wrongly think that I was going to bargain and of course I wasn't. Instead, I was just being honest about my situation— being short of money. I finally accepted her offer, remembering that I deserve kindness, too.
Another time, I noticed a friend of mine selling his old exercise bike, which was perfect for me, as I was looking to replace my broken one. I told him that I would take it when I had the money, but then life got in the way. When I finally got the time to pick it up, I realized my financial shortcomings again. I asked him if he could hold onto it for one more week, as then I'd have the funds again. He was happy to do this, but instead he insisted on offering me the bike as a gift. Another opportunity presents itself to teach me how to receive with dignity.
I continue to slowly learn how to accept the kindness from others. In fact, the relationship between giving and receiving is closely linked. When you accept the kindness from others with joy, they will feel happy, too.
1. How did the author feel at first when she received kindness from others?| A．Happy. | B．Unfair. | C．Proud. | D．Unacceptable. |
| A．Scare. | B．Independence. | C．Lack. | D．Principle. |
| A．Being punished. | B．Being misunderstood. |
| C．Accepting her coach's strict training. | D．Giving away the secret of her being short of money. |
| A．She got it for free. | B．She paid much money for it. |
| C．She bought it from her coach. | D．She borrowed it from her friend. |
【推荐2】Mr. Harris used to work in Dover, but then he changed his work, and he and his wife moved to another town. They did not have many friends there, but they soon met a lot of interesting people, and after a few weeks, they often went to dinner or to parties at other people’s houses. Then Mrs. Harris said to her husband, “We’ve been to a lot of other people’s houses, and now we must invite them to our house, mustn’t we?”
“Yes, certainly,” answered her husband, “A big party will be the easiest thing, won’t it? Then we can start to invite people to dinner in small numbers next month.”
So Mrs. Harris said, “Yes, I’ll invite all our friends here to a big party on 5th December.”
“How many will that be?” Mr. Harris asked. “Don’t invite too many.”
Mrs. Harris was beginning to write the invitations when her husband saw that she was writing, “Party: 6:30 to 8:30 p.m.”
“That isn’t very nice, is it?” he said. “You’re telling our guests that they must go at 8:30.” So Mrs. Harris just wrote “Party: 6:30 p.m.”
A lot of guests came, and they all had a good time, so they did not go home at 8:30. In fact they were still there at mid-night when the door bell rang and a policeman arrived. He said, “You must stop making a noise, because someone has complained.”
Mr. Harris said he did not want to quarrel with the policeman, so everyone went home. They were sorry to have to go.
When Mr. and Mrs. Harris were alone again, she said to him. “That was a surprise, wasn’t it? Who complained about the noise?”
“I did,” Mr. Harris answered in a tired voice.
1. Why did Mr. Harris and his wife move to another town?| A．They wanted to make some new friends. |
| B．Mr Harris changed his work. |
| C．They wanted to meet a lot of interesting people. |
| D．They enjoyed going to parties and visiting other people houses. |
| A．They had gone to other peoples parties many times. |
| B．They could ask people to dinner in small numbers. |
| C．They liked making friends with others |
| D．It was easy to hold a big party at home |
| A．From the morning till night. | B．About fourteen hours. |
| C．About two hours. | D．Till midnight. |
| A．At about 8: 30. |
| B．When the policeman talked with Mr Harris on the phone. |
| C．About twelve o'clock at midnight. |
| D．When someone telephoned the police station. |
【推荐3】We offer five kinds of courses. Each course has been designed to help students according to their needs.
Course 1: General English
General English is designed to develop students’ basic skills in: speaking and pronunciation, reading, listening, writing, grammar and vocabulary.
Tuesday to Friday: 9:00 am to 11:00 am, $288 per week.
Course 2: Academic English
Academic English is for students who want to take the IELTS exam or for those who need to use English in a professional area.
Monday to Friday: 4:00 pm to 5:00 pm, $320 per week.
Course 3: High School ESL
Why not make the most of your time studying in Australia with the help from TIES? We have High School ESL cases each week specifically designed for international students.
Tuesday to Friday: 8:00 am to 11:00 am, $25 per hour.
Course 4: Night Classes
Do you want to improve your English and get the best possible results in your GRE test We have two night classes each week designed to meet your needs.
Tuesday and Thursday evenings: 8:30 pm to 10:30 pm, $60 per day.
Course 5: One on One
If you are interested in some One on One lessons with TIES teachers, we can design a course to meet your needs. One on One lessons can improve your English language skills more quickly and help students who want to take TOEFL.
Tuesday to Friday: 2:00 pm to 5:00 pm.$80 per hour.
1. If you want to use English professionally, which choose should you choose?| A．General English | B．Academic English |
| C．High School ESL | D．Night Classes |
| A．$200. . | B．$300. | C．$500. | D．$600. |
| A．Its lessons are given in the morning. |
| B．It’s designed for English beginners. |
| C．It’s more expensive than the other courses. |
| D．Its lessons are designed only to improve writing skills. |
【推荐1】Each year, millions of visitors crowd into many national parks. With their unmatched beauty, the national parks offer people a place to go to restore their energy. The parks we enjoy today, however, might not be around without the past efforts of a few people who supported an idea to protect the natural beauty of our country.
One of these people was the naturalist John Muir. In 1867, on his way west to San Francisco, John Muir walked through Yosemite and quickly recognized its incomparable beauty. Muir devoted himself to learning as much about the wilderness as he could. Then, he would pass this learning on to others in the many articles he wrote describing the beauty of the area. In order to protect Yosemite from damage, Muir became the voice behind a government bill that would create Yosemite National Park. Soon other bills would follow, and Muir would continue his fight to make Americans understand the importance of protecting the wild. In 1901, Muir wrote a book about the national parks, which caught the attention of people all over the United States, including President Theodore Roosevelt.
At a young age,Theodore Roosevelt had shown signs of a passion that would strengthen throughout his lifetime. During a trip to North Dakota in 1883 he saw the damage done to the land and its wildlife.
Roosevelt would take his ideas about conservation with him to the White House as the country's 26th president. He would go on to create the U. S. Forest Service, 150 national forests, and 5 national parks. Roosevelt even canceled a 1903 presidential speaking tour in order to spend two weeks camping in Yellowstone, where he gave a speech calling for its protection. While visiting Yosemite, Roosevelt camped for three days with John Muir, who showed the president around and persuaded him to make Yosemite Valley a part of the larger Yosemite National Park. After the trip, Roosevelt commented that there was no better person in the world with whom to see and appreciate Yosemite.
The natural beauty that tourists from around the world enjoy today in the country's national parks is largely due to the efforts of Roosevelt and Muir, who devoted themselves to an idea that has benefited all people.
1. John Muir devoted himself to protecting Yosemite by__________________.| A．asking Americans to protect the wild |
| B．learning about the history of Yosemite |
| C．writing articles and putting forward bills |
| D．catching the attention of President Roosevelt |
| A．A trip with John Muir. |
| B．A trip to North Dakota. |
| C．A presidential speaking tour. |
| D．A camp experience in Yellowstone. |
| A．By explaining how he ran North Dakota. |
| B．By sharing others’ opinions of Roosevelt. |
| C．By comparing his work with that of John Muir. |
| D．By describing the things he did throughout his life. |
| A．enjoyed going camping together |
| B．worked together to create all the national parks |
| C．found a connection in their love of the wilderness |
| D．used their fame to bring attention to the environment |
【推荐2】Welcome to South Pole
Is it cold?
Yes! Be very careful out in the open air! The temperature is between -21℃ in the summer and -78℃ in the winter, and you can become numb with cold without realizing. There’s heavy frost even on the warmest summer days, and if it’s quiet you can hear your breath freeze. So if you leave the station, dress warmly and carry dry clothing and a portable radio.
Is there anything good about the weather?
The air is very pure, and it doesn’t snow very much — only about four millimetres a year. There’s very little wind and the sky is usually clear. It’s possibly the calmest place on Earth.
Is it safe?
Because the South Pole is a high altitude site, the glare of the sunlight here is very terrible. It’s also reflected by the snow, so if you go outside, remember to wear sunglasses and use suncream. If you don’t, there’s a severe risk that you’ll damage your eyesight or get badly sunburnt.
What’s it like to live here?
Life is quite abnormal. Sunrise and sunset come once every six months, and in the winter the total absence of daylight can be tiresome, and for some, depressing. We’re totally isolated except for radio and electronic communications, as no aircraft can fly here for about eight months. Usual equipment doesn’t always work as it should do. If you use an electric drill, the power cord will snap. Photography is tricky too, as film is fragile and the camera battery doesn’t work in the cold.
1. Which word best describes the South Pole most of the time？| A．Cool. | B．Freezing. | C．Cloudy. | D．Windy. |
| A．Raincoats. | B．Sunglasses. | C．Dry clothes. | D．Electronic communications. |
| A．To send an invitation. | B．To make a research. |
| C．To give some advice. | D．To introduce the South Pole. |
【推荐3】Today, Mars is a frozen desert with a thin atmosphere, too cold for liquid water to remain on the surface. Overwhelming evidence exists that Mars had liquid water oceans roughly 4 billion years ago. The question that drives our interests isn’t whether there’s life on present-day Mars. We are driven instead by asking whether there was life on Mars billions of years ago, which seems significantly more likely.
But if water existed on the Marian surface before, how was it possible? Mars is further away from the sun than Earth, and billions of years ago, the sun didn’t throw off as much heat as it does now.
The planet’s protective magnetic field mysteriously disappeared around 4.2 billion years ago as Mars cooled after forming. The sun’s solar wind then blew away the Martian atmosphere. leaving behind the thin one the planet has today.
Scientists believe the atmosphere was a key component for a warm, wet Mars that may have once hosted life. To have made the planet warm enough for liquid surface water, its atmosphere would likely have needed a large amount of greenhouse gas, carbon dioxide specifically.
Currently, we don’t know the carbon dioxide content of Mars ancient atmosphere. So the researchers turned to the Nordlinger Ries crater（陨石坑）in southern Germany. It was created by a meteorite（陨石）impact 15 million years ago. That geology and the chemistry of the site act as a good similar for the Martian surface.
Researchers will study the pH and nitrogen that might have been in ancient Martian water, which will show the carbon dioxide content in its ancient atmosphere. That will throw light on whether Mars was once warm enough to support life.
The Mars 2020 rover（探测器）will land in a similar crater next year, collecting samples that will be returned to Earth in a future mission. It could be 10 to 20 years before Mars samples are brought back to Earth. We might know the answer to one of the first questions once these samples are distributed to labs in the US and throughout the world.
1. What are people more interested in about Mars?| A．Whether there was ever life on Mars. | B．Whether there is life on Mars now. |
| C．Whether there was ever water on Mars. | D．Whether it is possible for life on Mars. |
| A．was too cold | B．had no water on it |
| C．lost its magnetic field | D．was too far from the sun |
| A．How this crater was formed. |
| B．Why Mars is not suitable for life. |
| C．Whether there is any life sign on Mars. |
| D．How much carbon dioxide is in Mars’ ancient atmosphere. |
| A．Mars samples will be brought back to earth in 2021. |
| B．Many countries take part in the research of Mars. |
| C．It takes at least ten years for people to reach Mars. |
| D．Mars samples will help discover all the secrets of Mars. |
