Life may have evolved on at least three planets within a newly discovered solar system 39 light years from Earth. Astronomers at the NASA have discovered no less than seven roughly Earth-sized worlds orbiting a dwarf star in the system. Scientists had previously identified a tiny number of "exoplanets", which are believed to have the qualities needed to support life. However, the new system contains an unprecedented(前所未有) number of Earth-sized, probably rocky planets, and is being acknowledged as an "accelerated leap forward" in the search for extraterrestrial (外星球的)life.

    Three of the new planets are said to be particularly promising because there might exist oceans. Thomas Zurbuchen, associate administrator of NASA, told a press conference in Washington: "This gives us a hint that finding a second Earth is not a matter of 'if', but 'when'."

    The planets were discovered using NASA's Spitzer Space Telescope, which was able to track how fast each of the planets crossed the star Trappist-l and completed an orbit. From this the research team calculated how far the planets were from their star, and therefore how likely they are to be habitable.

    NASA's Hubble Space Telescope is already being used to search for atmospheres around the planets. Future telescopes, including the proposed European Extremely Large Telescope and the James Webb Space Telescope, may be powerful enough to discover markers of life, such as oxygen in the atmospheres of exoplanets.

    Astronomers believe there could be as many as 40 billion potentially habitable worlds in our galaxy, the Milky Way. Prof Zurbuchen said that now was a "gold-rush phase" in the search for these exoplanets.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

Mid-IB at a glance

    The summer vacation is the time to strengthen your learning and prepare for the year ahead. In July and August Oxford Study Courses will once again hold its Mid-IB Summer School for students half way through their IB Diploma（国际预科证书）.

    We'll be back giving another generation of IB students a unique opportunity to sample a way of life enjoyed by students at famous universities.

    Students who have completed the first year of their IB Diploma can join us and we can help them prepare for their important second year.

    Students can choose how many subjects they study. Each subject is studied for one week. You can attend up to 5 weeks.

    The Mid-IB Summer School is held at Cambridge University in the UK （between June 20th and August 1 st） and at Harvard University and the Massachusetts Institute of Technology （MIT）in Boston, USA （between July 6th and July 25th）.

Student comments

◆ “The classes have shown me new approaches to learning. I have also learned how to approach exam questions and now feel confident in doing so.”

◆ “It was cool creating tight and close relationships with other students from around the world, realizing we all had a connection to each other.”

◆ “I really enjoyed the level of independence, although I felt like people were watching out for us. I also felt like an Oxford student!”

◆ “I have enjoyed the learning style and the course work has been extremely beneficial academically.”

Enjoy the summer

    Our Summer School gives you an action-packed social scene with visits to the fun places in the area, organized sports and social events, and advice on how to enjoy your free time in these amazing cities with your new friends. Welcome to contact us at ose@ose-ib.com or on +44（0）1865 521802!

    In 1978, I was 18 and was working as a nurse in a small town about 270 km away from Sydney, Australia. I was looking forward to having five days off from duty. Unfortunately, the only one train a day back to my home in Sydney had already left. So I thought I'd hitch a ride (搭便车).

    I waited by the side of the highway for three hours but no one stopped for me. Finally, a man walked over and introduced himself as Gordon. He said that although he couldn't give me a lift, I should come back to his house for lunch. He noticed me standing for hours in the November heat and thought I must be hungry. I was doubtful as a young girl but he assured （使…放心）me I was safe, and he also offered to help me find a lift home afterwards. When we arrived at his house, he made us sandwiches. After lunch, he helped me find a lift home.

Twenty-five years later, in 2003, while I was driving to a nearby town one day, I saw an elderly man standing in the glaring heat, trying to hitch a ride. I thought it was another chance to repay someone for the favour I'd been given decades earlier. I pulled over and picked him up. I made him comfortable on the back seat and offered him some water.

    After a few moments of small talk, the man said to me, “You haven't changed a bit, even your red hair is still the same.”

    I couldn't remember where I'd met him. He then told me he was the man who had given me lunch and helped me find a lift all those years ago. It was Gordon.

    Feifei, an 11-year-old boy from Xuzhou, Jiangsu Province, suffered from a sudden acute eye disease which has almost led to blindness. The disease was caused when he overused his eyes during the winter vacation, during which he played computer games for continuous 10 days and nights.

    Many youngsters in China nowadays are increasingly addicted to computer games and other electronic products. This is followed by a series of health problems, with the most typical case being myopia, or nearsightedness.

    According to the latest research report released by the World Health Organization (WHO),the myopia rate among Chinese teenagers ranks first in the world—70 percent of high school and college students. The rate is nearly 40 percent in primary school students, while it is only 10 percent for their peers in the United States.

    There are at least 10 million people in China with severe myopia, and they are likely to get pathological myopia（病理性的近视） in middle age. Pathological myopia can't be treated with glasses or surgery, and it is one of the biggest factors that lead to blindness, Xu Xun, an expert at Shanghai General Hospital, pointed out.

    Experts explain that two major factors lead to the high rate of myopia among Chinese people. One is high academic pressure, and the other one is excessive use of electronic devices over a long period of time. Genetics, on the other hand, are not the main reason, as only 20 percent of Chinese people had myopia in the 1960s.

    "Teenagers are now faced with severe academic pressure, which means they often study without natural light. This increases their risk of becoming nearsighted," Xu said. Experts suggest that youngsters maintain a proper balance between study and rest so as to protect their eyesight, and parents should play an active role in the process.

    Ever walked to the shops only to find, once there, you've completely forgotten what you went for? Or struggled to remember the name of an old friend? For years we've accepted that a forgetful brain is as much a part of aging as wrinkles and gray hair. But now a new book suggests that we've got it all wrong.

    According to The Secret Life of the Grown-up Brain, by science writer Barbara Strauch, when it comes to the important things, our brains actually get better with age. In fact, she argues that some studies have found that our brain hits its peak between our 40s and 60s — much later than previously thought.

    Furthermore, rather than losing many brain cells as we age, we keep them, and even produce new ones well into middle age. For years it's been assumed that brain, much like the body, declines with age. But the longest, largest study into what happens to people as they age suggests otherwise.

    This continuing research has followed 6,000 people since 1956, testing them every seven years. It has found that on average, participants performed better on cognitive (认知的) tests in their 40s and 50s than they had done in their 20s. Specifically, older people did better on tests of vocabulary, verbal memory (how many words you can remember) and problem solving. Where they performed less well was number ability and perceptual speed — how fast you can push a button when ordered. However, with more complex tasks such as problem-solving and language, we are at our best at middle age and beyond. In short, researchers are now coming up with scientific proof that we do get wiser with age.

    Neuroscientists are also finding that we are happier with aging. A recent US study found older people were much better at controlling and balancing their emotions. It is thought that when we're younger we need to focus more on the negative aspects of life in order to learn about the possible dangers in the world, but as we get older we've learned our lessons and are aware that we have less time left in life: therefore, it becomes more important for us to be happy.