The streams are about 12 to 15 feet wide and 300 feet or more long, scientists said. "What we're dealing with is wet soil, thin layers of wet soil, not standing water," said Aifred  McEwen of the University of Arizona at Tueson! the principal scientist for the Mars Reconnaissance Orbiter's high-resolution imaging experiment,

     Because liquid water is essential to life, the findings could have major implications for the possibility of Martianlife, There searchers said further exploration is needed to determine whether microscopic life exists on the planet.

    The presence of liquid water could also make life easier for astronauts visiting or living on Mars. Watercould be used for drinking and for creating oxygen and rocket fuel. NASA's goal is to send humans there inthe 2030s.

    The evidence of flowing water consistslargely of dark, narrow streaks(条痕) on the surface that tend to appear and growd uring the warmest Martian months and fade the rest of the year.

    Mars is extremely cold even in summer,and the streaks are in places where the temperature is as low as minus 10 degrees Fahrenheit. But salt can lower the freezing point of water and melt ice.

    The source of the water is a mystery. Scientists noted it could be melting ice. It could be an underground a quifer, which is rock or sand that can hold water. It is possibly water vapor from the thin Martian atmosphere, Or it may be a combination Michael Meyer, lead scientistfor NASA's Mars exploration program, said the only definitive way for now to determine whether there's life on Mars is to collect rocks and soil foranalysis on Earth - something a U.S. lander set for lift-off in 2020 will do.

    The book ABigFatCrisis: TheHiddenForcesBehindObesityEpidemic— andHowWeCanEndIt by Deborah Cohen, a senior natural scientist, is very popular now. {#blank#}1{#/blank#} But according to this book, the following are some misunderstandings of obesity or being overweight.

1)．If you're obese, blame your genes.

    {#blank#}2{#/blank#} Yet, between 1980 and 2000, the number of Americans who are obese has doubled—too quickly for genetic factors to be responsible. At restaurants, a dollar puts more calories on our plates than ever before, because restaurant meals usually have more calories than what we prepare at home, so people who eat out more frequently have higher rates of obesity than those who eat out less.

2)．If you're obese, you lack self­control.

    Research shows that if we are faced with too much information, we have a tendency to make poor choices on diet. {#blank#}3{#/blank#} Even, the most vigilant(警觉的)people may not be good controllers of themselves.

3)．{#blank#}4{#/blank#}

    Although the US Department of Agriculture estimates that fewer than 5 per cent of Americans live in the “food deserts”， about 65 per cent of the nation's population is obese. For most of us, obesity is not related to access to more fresh fruits and vegetables, but to the choices we make in supermarkets.

4)．The problem is not that we eat too much, but that we don't exercise.

    Michelle Obama's “Let's Move” campaign is based on the idea that if kids exercise more, childhood obesity rates will decrease. {#blank#}5{#/blank#} In fact, although a drop in work­related physical activity may explain up to 100 fewer calories burned, leisure physical activity appears to have increased.

    Tom goes everywhere with Catherine Green, a 54-year-old secretary. He moves around her office at work and goes shopping with her. "Most people don't seem to mind Tom," says Catherine, who thinks he is wonderful. "He's my fourth child," she says. She may think of him and treat him that way as her son, buying his food, paying his health bills and his taxes, but in fact Tom is a dog.

    Catherine and Tom live in Sweden, a country where everyone is expected to lead an orderly life according to rules laid down by the government, which also provides a high level of care for its people. This level of care costs money.

    People in Sweden pay taxes on everything, so aren't surprised to find that owning a dog means yet more taxes. Some people are paying as much as 500 Swedish kronor in taxes a year for the right to keep their dog, money that is spent by the government on dog hospitals and sometimes medical treatment for a dog that falls ill. However, most such treatment is expensive, so owners often decide to offer health and even life premium for their dog.

    In Sweden dog owners must pay for any damage their dog does. A Swedish Kennel Club official explains what this means: if your dog runs out on the road and gets hit by a passing car you, as the owner, have to pay for any damage done to the car, even if your dog has been killed in the accident.

    We all love bank holidays. In the UK, we only get eight bank holidays in one year, and at least five of those occur around Christmas time and Easter time! A bank holiday is a British English term. This is an official day that is decided by the government, when banks, shops and offices close for the day even though it's a weekday—usually a Monday, and a lot of people have a day off work.

    Bank holidays are different in Colombia—firstly, they are called “festivos”. There are twenty festivos for the whole country in one year! In Britain ，people get more holiday allowance(津贴)than Colombians but fewer bank holidays. There can be even more festivos in Colombia, depending on which region of Colombia you live in. This is because different regions have their own holidays. For example, some regions have a patron saint(守护神) in their region, so they have an extra festivo to celebrate that saint.

    However, there are some days that are national holidays for historical reasons. There is an Independence Day celebration on July 20 every year. This is just like Bastille Day in France on July 14, or Independence Day in the United States on July 4. Other important festivos in Colombia are :Labour Day, on May 1, and Columbus Day on October 12. Columbus Day is a historical bank holiday that almost every county on the continent of America celebrates. This includes Colombia, Chile, Peru, Argentina, Mexico and the United States. It is a memorialization of the day that the Italian sailor, Christopher Columbus, first reached land on the continent in the year 1492. Many people criticize this day and say it is not something to celebrate because of the way Columbus and his teams treated the people that were already living there.

    Sometimes people come into your life and you know at once that they were sure to be there. They serve some sort of on purpose, teach you a lesson or help find out who you are or who you want to become. You never know who these people may be: your classmate, neighbor, teacher, long-lost friend or even a real stranger. But you know that every moment they will affect your life in some serious way.

    Sometimes things happen to you. At the time they may seem terrible, painful and unfair. But later you realize that without getting over those difficulties you would have never realized your further ability and strength. Everything happens for a reason and nothing happens by chance or with good or bad luck.

    The people you meet affect your life, and the successes and failures(失败) you experience, create who you are. Even the bad experiences can be learned from. In fact, they are probably the most poignant and important ones.

    Enjoy every day even every moment and take from it everything that you possibly can, for you may never be able to experience it again. Talk to people you have never talked to before, and really listen. You should set your sights high, hold your head up, tell yourself you are a great one and believe in yourself.

    You can make your life anything you wish. Create your own life and then go out and live it.

    Scientists have connected the "fat gene" with the "happy gene". They believed there could be genetic evidence which explains why fat people are often happier than their skinny friends. The breakthrough could be an explanation for why fat characters, such as The Laughing Policeman and Father Christmas are often described as joyful and kind.

    FTO is the major genetic contributor to being fat. But it is also connected with an eight percent reduction in the risk of depression. Researchers at McMaster University in Canada had been studying whether there was a connection between being fat and being depressed. They found the opposite was true.

    They studied 17, 200 DNA from participants in 21 countries. Results showed people with FTO gene—the fat gene—showed less signs of depression. This finding was supported by three additional international studies.

    Professor David Meyre said, "We set out from the belief that being depressed and being fat both deal with brain activity. We thought that fat genes may be related to depression. However, we have discovered a molecule (分子) contributing to depression. It is the first evidence that an FTO fat gene is connected with protection against depression.

    In a recent interview, actress Lisa Riley said she was more than comfortable with her size. She said she is a "big, really happy" girl who is lucky enough to be confident in her own skin, and added, "Many people want to be thinner. Not me. I love being different and it drives me mad that people don't believe I'm happy with what I am."