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.

    In 1975, George Carlin appeared on a popular TV show, Saturday Night Live, with his famous words about blue food. “Why is there no blue food? I can't find blue food—I can't find the flavor of blue! I mean yellow is lemon; orange is orange and red is cherry. Where is the blue food?”

    Well, Carlin pretty much has it right—there is not no blue food, but there's certainly not a lot of it. Fresh-picked blueberries are blue, though they become purple when they are turned into jam. The blue in blueberries—like the purple in grapes and red in tomatoes—is found in nature. But it isn't a hot color for food. People don't seem to prefer blue food. Some diet programs even suggest that those determined to lose weight should make their food blue.

    Eating, in part, begins with our eyes. Chares Spence—an experimental psychologist from Oxford University—points out that color can change our taste experience. Commonly, we consider red-colored foods up to 20% sweeter than they actually are; and green foods as being more sour. Spence suggests: human expectations may be influenced by our long history of watching—green fruits can become sweet as they grow up and turn red.

    But what about blue? Except blueberries, much of the blue food we see these days is dyed blue artificially. Food producers argue that artificial color doesn't do much damage to health. A lot of research shows that some physical problems of kids are related to food dyes—while other studies show no effects at all. Blue birthday cake or even blue-dyed chicken can be served on the dinner table. So what?

    This brief book is aimed at high school students, but speaks to anyone learning at any stage of life.

    Its formal, serious style closely matches its content, a school-masterly book on schooling. The author, W. H. Armstrong, starts with the basics: reading and writing. In his opinion, reading doesn't just mean recognizing each word on the page; it means taking in the information, digesting it and incorporating it into oneself just as one digests a sandwich and makes it a part of himself. The goal is to bring the information back to life, not just to treat it as dead facts on paper from dead trees. Reading and writing cannot be completely separated from each other; in fact, the aim of reading is to express the information you have got from the text. I've seen it again and again: some one who can't express an idea after reading a text is just as ineffective as someone who hasn't read it at all.

    Only a third of the book remains after that discussion, which Armstrong devotes to specific tips for studying languages, math, science and history. He generally handles these topics thoroughly and equally, except for some weakness in the science and math sections and a bit too much passion (激情) regarding history to his students, that was a hundred times more than my history teachers ever got across. To my disappointment, in this part of the book he ignores the arts. As a matter of fact, they demand all the concentration and study that math and science do, though the study differs slightly in kind. Although it's commonly believed that the arts can only be naturally acquired, actually, learning the arts is no more natural than learning French or mathematics.

    My other comment is that the text aged. The first edition apparently dates to the 1960s—none of the references(参考文献) seem newer than the late 1950s. As a result, the discussion misses the entire computer age.

    These are small points, though, and don't affect the main discussion. I recommend it to any student and any teacher, including the self-taught student.

    HandEnergy is an ingenious apple-sized device that charges your phone anytime, anywhere. But what really makes this thing special is the fact that it uses your own personal energy to do it.

    In a time where power-banks and solar-power devices have become mainstream, a device that lets you charge gadgets on the go doesn't sound very special. But while power-banks have to be charged the old fashioned way, and solar panels need the sun to store energy.

    Hand Energy just needs a hand. To get this little guy to produce energy, which it then stores in built-in batteries, all you have to do is hold it in your hand and rotate your wrists.

    To use Hand Energy, users start by winding a starter ring. This transmits a signal to activate the rotor, at which point they can start rotating their wrists to keep the rotor spinning. It might sound hard to believe, but the rotor inside Hand Energy spins at an average speed of 5,000 rotations per minute, transmitting mechanical power to create an electric current, and charging the built-in batteries. To charge a device, all you have to do is hook it up to HandEnergy using a USB cable.

    Hand Energy was successfully crowd funded on Kickstarter, raising over $71,000 in one month, and will be available for the masses in May 2017, at a price of 99 euros. One thing is for sure – it beats paying thousands of dollars on a solar-powered gadget-charging coat.

    Some parents can't resist the strong desire to help their children play hooky (逃学) for a trip. Five-year-old Erica and her siblings Alex, 9, and Kate, 12, missed school in Denver on Aug. 21, 2017. Their father Mr. Reed took them on a camping trip to Halsey to see the solar eclipse (日食). Kate had told her teachers she'd be absent and Mr. Reed let Erica's and Alex's teachers know, too. But he didn't ask for permission.

    Mr. Reed has loved astronomy since seeing Neil Armstrong walk on the moon on his sixth birthday. He says, “I want my own kids to have a similar kind of wonderment and hope about future discoveries.”

    Parents often dream of traveling with their children to teach them about science, geography and culture. Many teachers support them, as the Reed children's teachers did. Other teachers were angry about the extra work.

    Teacher Amanda says she feels frustrated when parents take students out of school for family trips. If she sends homework, she finds it's often returned incomplete or incorrect, because the absent student didn't hear her explanation in class. Some students suffer anxiety as they struggle to catch up. Research shows that students who are absent often, for any reason—excused or unexcused—performed more poorly in school.

    Garrick agreed to miss five days of school for the Antarctic trip last year as a senior high school student, however. Managing the homework was a challenge, but it helped him gain time management skills. “And the trip is worth the effort,” he says, “sparking his interest in international relations. You can't really put a price on changing your world view,” Garrick says. “That's what travel has done for me. It has changed how I think about things.”

    A famous doctor once received a little child who was badly ill. Thanks to his skill and care, his young patient got well and was soon able to get up and run about again.

    The child's mother was very much obliged to the doctor, and she called on him to thank him for what he had done for her child. "Doctor," she said, "you have saved my little son. I don't know how to thank you enough. I feel that money alone cannot repay you, so I have made this little purse with my own hands, as a sign of my gratitude. I hope you will accept it." The doctor stood up and said coldly, "Madam, a little present like that is very nice between friends, but a doctor needs to be paid properly for what he has done." The lady was so surprised and hurt so much that she could not reply for a moment. Then she said quietly, "Perhaps you will tell me how much your fee is?"

    "Fifty pounds", he answered.

    The lady opened the little purse and took out four fifty-pound bank notes. She handed one of them to the doctor, and put the other three back into the purse. She put the purse into her handbag and, saying good bye to the doctor, went out of the room.