Scientists have been puzzled by the phenomenon that migrating birds fly not just in groups all the time, but in "V" formations and they have tried to figure out what benefit birds get from this particular formation. Now, a research group from University of London may have found the answer ― migrating birds fly in a "V" to save energy, according to a study published in the journal Nature.
When a bird flaps(振翅) its wings, it stirs the air around it and causes it to move indifferent directions. Scientist found in the study that the air creates an upward-moving wave at the tips of the wings, which means that if a bird flies around the wingtips of another bird, it can get a boost（抬高） from the rising air and therefore use less energy to stay in the air.
Apart form the "free ride" strategy, scientists were also surprised to observe that migrating birds timed their wing beats and adjusted their positions in a very precise way to maximize the lifting effect while avoiding areas where the air move downward.
"They're able to sense what's going on from the bird in front, where this 'good air' is coming from and now how to position themselves perfectly in it," lead researcher Steven Portugal told BBC.
In fact, the "V" formation has long thought to help birds fly more efficiently(效率搞地). A previous study showed that birds' heart rates went down when they were flying together in a "V" formation. Jet fighters were also found to be able reduce their energy use by up to 18% by staying near the wingtips of other jet fighters. Both of these findings led scientists to suspect that the "V" formation had an efficiency purpose, but until now they still lack proof.
"For scientists, the new study provides an insight into an interesting natural phenomenon. But it could mean even more for aircraft companies — helping them understand how they can imitate that with their plane formations to save fuel, said Portugal."What is the author's purpose in writing this article?
| A．To explain how birds benefit from migration. |
| B．To introduce how migrating birds find their way. |
| C．To tell some applications of migrating birds' "V" formations. |
| D．To report new findings about migrating birds' "V" formations. |
According to the recent study, when birds migrate .
| A．they don't change their lead birds during the whole journey |
| B．they fly in "V" formations to protect themselves against enemies |
| C．they form the shape of a "V" to make best use of the lifting effect |
| D．the air they stir around makes it hard for the birds behind to fly fast |
What is the significance of the new study according to this article?
| A．It might inspire aircraft companies to think of ways to improve efficiency. |
| B．It has proved that the "V" formation can improve in efficiency in many fields, |
| C．It has led scientists to discover that birds' heart rates go down when they fly in a "V". |
| D．It shows that the best formation of jet fighters in battle should be a "V" formation. |
The underlined word "imitate" in the last paragraph most probably means " ".
| A．use | B．copy | C．change | D．learn |
Below is a selection from a popular science book.
| If blood is red, why are veins (静脉) blue? Actually, veins are not blue at all. They are more of a clear, yellowish color. Although blood looks red when it’s outside the body, when it’s sitting in a vein near the surface of the skin, it’s more of a dark reddish purple color. At the right depth, these blood-filled veins reflect less red light than the surrounding skin, making them look blue by comparison. Which works harder, your heart or your brain? That kind of depends on whether you’re busy thinking or busy exercising. Your heart works up to three times harder during exercise, and shifts enough blood over a lifetime to fill a supertanker（超级油轮）. But, in the long run, your brain probably tips it, because even when you’re sitting still your brain is using twice as much energy as your heart, and it takes four to five times as much blood to feed it. Why do teeth fall out, and why don’t they grow back in grown-ups? Baby (or “milk”) teeth do not last long; they fall out to make bigger room for bigger, stronger adult teeth later on. Adult teeth fall out when they become damaged, decayed（腐烂）and infected by bacteria. Once this second set of teeth has grown in, you’re done. When they’re gone, they are gone. This is because nature figures you’re set for life, and what controls regrowth of your teeth switches off. Do old people shrink（收缩）as they age? Yes and no. Many people do get shorter as they age. But, when they do, it isn’t because they’re shrinking all over. They simply lose height as their spine (脊柱) becomes shorter and more curved due to disuse and the effect of gravity (重力). Many (but not all) men and women do lose height as they get older. Men lose an average of 3-4 cm in height as they age, while women may lose 5 cm or more. If you live to be 200 years old, would you keep shrinking till you were, like 60 cm tall, like a little boy again? No, because old people don’t really shrink! It is not that they are growing backwards—their legs, arms and backbones getting shorter. When they do get shorter, it’s because the spine has shortened a little. Or, more often, become more bent and curved. Why does spinning make you dizzy)? Because your brain gets confused between what you’re seeing and what you’re feeling. The brain senses that you’re spinning using special gravity-and-motion-sensing organs in your inner ear, which work together with your eyes to keep your vision balance stable. But when you suddenly stop spinning the system goes out of control, and your brain thinks you’re moving while you’re not. Where do feelings and emotions come from? Mostly from an ancient part of the brain called the limbic system（边缘系统）. All mammals have this brain area — from mice to dogs, cats, and humans. So all mammals feel basic emotions like fear, pain and pleasure. But since human feelings also involve other, newer bits of the brain, we feel more complex emotions than any other animal on this planet. If exercise wears you out, how can it be good for you? Because our bodies adapt to everything we do to them. And as far as your body is concerned, it’s “use it, or lose it”! It’s not that exercise makes you healthy, it’s more that a lack of exercise leaves your body weak and easily affected by disease. |
What is the color of blood in a vein near the surface of the skin?
| A．Blue | B．Light yellow |
| C．Red | D．Dark reddish purple |
Why do some old people look a little shrunken as they age?
| A．Because their spine is in active use. |
| B．Because they are more easily affected by gravity. |
| C．Because they keep growing backwards. |
| D．Because their spine becomes more bent. |
Which of the following statements about our brain is true?
| A．In the long run, our brain probably works harder than our heart. |
| B．When our brain senses the spinning, we will feel dizzy. |
| C．The brains of the other mammals are as complex as those of humans. |
| D．Our feelings and emotions come from the most developed area in our brain. |
What is the main purpose of the selection?
| A．To give advice on how to stay healthy. |
| B．To provide information about our body. |
| C．To challenge new findings in medical research. |
| D．To report the latest discoveries in medical science. |
Jimmy is an automotive mechanic, but he lost his job a few months ago. He has good heart, but always feared applying for a new job.
One day, he gathered up all his strength and decided to attend a job interview. His appointment was at 10 am and it was already 8:30. While waiting for a bus to the office where he was supposed to be interviewed, he saw an elderly man wildly kicking the tyre of his car. Obviously there was something wrong with the car. Jimmy immediately went up to lend him a hand. When Jimmy finished working on the car, the old man asked him how much he should pay for the service. Jimmy said there was no need to pay him; he just helped someone in need, and he had to rush for an interview. Then the old man said, “Well, I could take you to the office for your interview. It’s the least I could do. Please. I insist.” Jimmy agreed.
Upon arrival, Jimmy found a long line of applications waiting to be interviewed. Jimmy still had some grease (油腻物) on him after the car repair, but he did not have much time to wash it off or have a change of shirt. One by one, the applicants left the interviewer’s office with disappointed look on their faces. Finally his name was called. The interviewer was sitting on a large chair facing the office window. Rocking the chair back and forth, he asked, “Do you really need to be interviewed?” Jimmy’s heart sank. “With the way I look now, how could I possibly pass this interview?” he thought to himself.
Then the interviewer turned the chair and to Jimmy’s surprise, it was the old man he helped earlier in the morning. It turned out he was the General Manager of the company.
“Sorry I had to keep you waiting, but I was pretty sure I made the right decision to have you as part of our workforce before you even stepped into the office. I just know you’d be a trustworthy worker. Congratulations!” Jimmy sat down and they shared a cup of well-deserved coffee as he landed himself a new job.Why did Jimmy apply for a new job?
| A．He was out of work | B．He was bored with his job |
| C．He wanted a higher position | D．He hoped to find a better boss |
What did Jimmy see on the way to the interview?
| A．A friend’s car had a flat tyre | B．a wild man was pushing a car |
| C．a terrible accident happened | D．an old man’s car broke down |
Why did the old man offer Jimmy a ride?
| A．He was also to be interviewed | B．He needed a traveling companion |
| C．He always helped people in need | D．He was thankful to Jimmy |
How did Jimmy feel on hearing the interviewer’s question?
| A．He was sorry for the other applicants |
| B．There was no hope for him to get the job |
| C．He regretted helping the old man |
| D．The interviewer was very rude |
Deputy Agriculture Secretary Kathleen Merrigan sees an epidemic (流行病) sweeping across Americas farmland. It has little to do with the usual challenges, such as flood, rising fuel prices and crop-eating insects. The country's farmers are getting older, and there are fewer people standing in line to take their place. National agricultural census (普查) figures show that the fastest-growing group of farmers is the part over 65. Merrigan is afraid the average age will be even higher when the 2012 statistics are completed.
Merrigan, a former college professor, is making stops at universities across the country in hopes of encouraging more students to think about careers in agriculture. Aside from trying to stop the graying of America's farmers, her work is made tougher by a recent blog posting that put agriculture at No.1 on a list of "useless" college degrees. Top federal agriculture officials are talking about the posting, and it has the attention of agricultural organizations across the country.
“There couldn't be anything that's more incorrect," Merrigan said. "We know that there aren't enough qualified graduates to fill the jobs that are out there in American agriculture.
In addition, a growing world population that some experts predict will require 70% more food production by 2050, she said.
“I truly believe we're at a golden age of agriculture. Global demand is at an all-time record high, and global supplies are at all-time record lows," said Matt Rush, director of the Texas Farm Bureau. "Production costs are going to be valuable enough that younger people are going to have the opportunity to be involved in agriculture”.
The Department of Agriculture has programs aimed at developing more farmers and at increasing interest in locally grown food. The National Young Farmers' Coalition has also been pushing for state and federal policy changes to make it easier for new fermers.
Ryan Best, president of Future Fanners of America, has been living out of a suitcase, traveling the country and visiting with high school students about careers in agriculture. The 21 -year-old Best hopes his message-that this is a new time in agriculture-will motivate the next generation to turn around the statistics.“Never before have we had the innovations (创新）in technology which have led to agriculture in this country being the most efficient it has ever been” he said. “There’s really a place for everybody to fit in”What is the new challenge to American agriculture?
| A．Fewer and older farmers. | B．Higher fuel prices. |
| C．More natural disasters. | D．Lower agricultural output. |
Why is Merrigan visiting universities across the country?
| A．To draw federal agriculture officials' attention |
| B．To select qualified agriculture graduates. |
| C．To clarify a recent blog posting. |
| D．To talk more students into farming careers |
According to Matt Rush, American agriculture will provide opportunities for younger people because__________.
| A．the government will cover production costs |
| B．global food supplies will be even lower |
| C．investment in agriculture will be profitable |
| D．America will increase its food export |
What do the underlined words "to turn around the statistics" in the last paragraph mean?
| A．To re-analyze the result of the national census. |
| B．To increase production. |
| C．To bring down the average age of farmers. |
| D．To invest more in agriculture. |
Keeping a busy social life among lots of friends may keep people thinner than spending hours doing some exercises, according to scientists. They say that socializing and meeting with friends help increase levels of brown fat in the body which burns calories to produce heat.
Living in an exciting social environment was found to reduce fat in mice's belly by half over four weeks, even if they ate more. US researchers say that social excitement aids weight loss by turning white fat into brown. White fat stores calories and makes us fatter, while brown burns energy to produce heat. Turning white fat into brown is extremely difficult, normally requiring long- term stay in cold conditions or exciting part of the body's nervous system.
However, scientists from Ohio State University now think that having a busy social life is an even more effective way of changing white fat into brown. The team came up with their theory by studying the effects of various living environments on mice. Those, who lived alongside a greater number of mice, had more space and toys to excite themselves and then lost far more weight over the course of the study than their “couch potato" fellows.
Study author, Dr Matthew During, whose team's findings appear in the journal Cell Metabolism, said, "I'm still amazed at the degree of fat loss that occurs." Explaining how new technology had threatened face-to-face socializing, he added, "It's not just a sedentary(久坐的) lifestyle and high calorie foods, but an increasing lack of social activities." Co-author Dr Lei Cao said，"Loneliness is a potential factor for cancer and death; it's equal to cigarette smoking to a certain extent. Social activities are very vital. What information can we get from the first two paragraphs?
| A．Brown fat stores calories and makes us fatter |
| B．It doesn't take long to turn white fat into brown. |
| C．Social excitement helps gain more weight |
| D．Brown fat can burn energy to produce heat. |
Which of the following statement does the text support?
| A．Levels of brown fat can be increased by socializing. |
| B．The mice lacking social life lose more weight. |
| C．The research findings haven't been published so far. |
| D．Dr Matthew During wasn't convinced of the result. |
We can conclude from the text that _______.
| A．the fat in mice's belly was reduced because of the relaxing environment |
| B．a sedentary lifestyle and high calories foods influence people's social life |
| C．surfing the Internet may influence people's face-to-face communication |
| D．cancer and death are mainly caused for lack of social life |
What’s the main idea of the text?
| A．Brown fat is beneficial to people's health. |
| B．Socializing is unnecessarily important in people's daily life. |
| C．White fat can be changed into brown fat. |
| D．Socializing contributes to people's losing weight. |
What you have just read is a _______.
| A．note | B．report | C．schedule | D．poster |
What is going to take place on 2 February, 2013?
| A．A party for close friends to meet and have fun |
| B．A party to celebrate a traditional festival. |
| C．A big event to welcome a Chinese new year. |
| D．A social gathering to raise money for wildlife. |
Which of the following statements is true?
| A．Tickets are sold in Kwun Tong High School |
| B．It's unnecessary to take soft drinks with you. |
| C．Free digital cameras are provided for everybody |
| D．Festival food will be served without extra charge. |