The Americans believe that anybody can become president of the United States. In a recent Hollywood comedy, that is exactly what happens.

    Dave Kovic, played by Kevin Kline, is a kind-hearted man who runs a business that finds people jobs. He leads a typical American way of life, except for one thing－he looks exactly like the president, Bill Mitchell. In fact, the only thing that makes him different from the nation's leader is that he is very nice!

    The president has started using look-alikes during some public appearances. Dave is offered a chance to “serve his country” by becoming one. However, things go wrong. The president becomes very ill and Dave ends up acting as the president forever.

    Director Ivan Reitman, who made the popular and successful comedies like Twins, Ghostbusters and Legal Eagles, could have gone for easy laughs by making fun of the American government. Instead, Dave is an attractive comedy about an ordinary man in extraordinary situations. Kevin Kline gives a double performance as Dave and the president, and Sigourney Weaver is at her best as his First Lady. The love story that develops between her role and Dave is a real classic.

    The film is 100% American. However, if you've ever felt that anybody could do a better job running the country than the people in power, then you'll enjoy Dave!

    "If you want to see a thing well, reach out and touch it!"

That may seem a strange thing to say. But touching things can help you to see them better.

    Your eyes can tell you that a glass ball is round. But by holding it in your hands, you can feel how smooth and cool the ball is. You can feel how heavy the glass is. When you feel all these about the ball, you really see it. With your skin, you can feel better. For example, your fingers can tell (辨别) the difference between two coins in your pocket. You can feel a little drop of water on the back of your hand, too. You can even feel sounds against your skin. Have you ever wanted to know why some people like very loud music? They must like to feel the sounds of music.

    All children soon learn what "Don't touch!" means. They hear it often. Yet most of us keep on touching things as we grow up. In shops, we touch things we might buy: food, clothes. To see something well, we have to touch it. The bottoms of our feet can feel things, too. You know this when you walk on warm sand, cool grass or a hard floor. All feel different under your feet.

    There are ways of learning to see well by feeling. One way is to close your eyes and try to feel everything that is touching your skin. Feel the shoes on your feet, the clothes on your body, the air on your skin. At first, it is not easy to feel these things. You are too used to them!

    Most museums are just for looking. But today some museums have some things to touch. Their signs say, "Do touch!" There you can feel everything on show.

    If you want to see better, reach out and touch. Then you will really see!

    It may appear strange to hear that crops are making headlines.But this is no ordinary produce—these fruits and vegetables have been grown in simulated（模拟的）Martian and lunar soils!

    Though the possibility of growing crops in outer space only gained widespread interest after Matt Damon grew potatoes in the movie "The Martian",scientists have been testing the idea for many years.Fresh produce will after all be the key to setting up space colonies（殖民地）.

    Among the pioneers in this effort is a team led by Wieger Wamelink,a scientist at Netherland's Wageningen University.In 2013,they planted fourteen varieties of plants in simulated Martian and lunar soils.Though the "Mars" plants did not bear any produce,they grew better than the "lunar" plants,most of which died shortly after being planted.Lack of vapor in the soil,according to the scientists,might have accounted for the failure.

    The second experiment began in late 2015.The researchers selected the same crops,while this time they used larger containers and added grass to them.In March 2016,their efforts were rewarded with a variety of produce including the vegetable that kept "The Martian" alive: potatoes.

    However,the researchers were still not sure if the produce was safe to eat.That's because the Martian and lunar soils contain heavy metals like lead and arsenic,which do not affect plants but are poisonous to humans.

    After months of testing,earlier this week,the team finally confirmed that the produce was safe for human consumption.Some of the crops even contained lower levels of heavy metals than plants grown in the "ordinary" earth soil.

    To celebrate the success,the scientists held a dinner party that centered ground the crops.While there is no word on how the food tasted,it sure looks delicious.

    Driverless technology will soon enter another major global industry: shipping. Several companies recently announced plans to start self-sailing ships to improve safety and efficiency（效率）.

    One of them is Norwegian chemical company Yara International. Yara has designed to build an autonomous ship expected to start next year. The ship is fully electric to reduce air pollution. It is designed to carry containers normally transported by truck. This means the ship will also improve road safety by replacing about 40,000 truck trips a year.

    Yara plans to operate the ships by remote control beginning sometime next year. By 2020, the ships should be loading and sailing themselves. Another company focusing on self-sailing ships is the world's largest mining company, Australia's BHP Billiton. The company's Vice President of Freight, Rashpal Bhatti, recently spoke about the technology. He said, “I believe automation（自动化）will be one of the biggest changes for shipping in the future.” Autonomous ships offer important chances to improve safety and provide better efficiency results to the marine supply chain. He added that self-sailing ships could become a reality within the next decade.

    Rolls-Royce, the British automobile and engine manufacturer, is also developing unmanned shipping technologies. Oskar Levander is the company's head of marine operations. He told a conference last year, “This is happening. It's not if, it's when.” Several shipping companies have invested hundreds of millions of dollars to develop self-sailing ships expected to be used by 2025. These ships will be equipped with technology to collect weather and sea data. They will then use the data to plan out the safest, shortest and most fuel-efficient route.

    Elephants have impressed us for centuries. They are big, clever, and sociable. But what if someone told you that they may also hold the key to fighting cancer (癌症)?

    People have been wondering why elephants do not develop cancer, even though they have lifespans (寿命) that are similar to humans, living for around 50 to 70 years.

    Now scientists believe they know why. A team at the University of Chicago, US has found that elephants carry a large number of genes that stop tumors (肿瘤) from developing. To be precise, they found 20 copies of an anti­tumor gene called TP53 in elephants. Most other species, including humans, only carry one copy.

    According to the research, which was recently published on the online science network BioRxiv, the extra copies of the gene improved the animal's sensitivity to DNA damage. This lets the cells quickly kill themselves when damaged before they can go on to form deadly tumors.

    “An increased risk of developing cancer has stood in the way of the evolution of large body sizes in many animals，” study author Dr. Vincent Lynch told The Guardian. If every living cell (细胞) has the same chance of becoming cancerous, large creatures with long lifespans like whales and elephants should have a greater risk of developing cancer than humans and mice do. But across species, the risk of cancer does not show a connection with body mass.

    This_phenomenon was found by Oxford University scientist Richard Peto in the 1970s and later named "Peto's paradox". Evolutionary (进化的) biologists believe it results from larger animals using protection that many smaller animals do not. In the elephant's case, the making of TP53 is nature's way of keeping this species alive.

    The study also found that when the same genes were brought to life in mice, they had the same cancer resistance (抵抗) as elephants. This means researchers could use the discovery to develop new treatments that can help stop cancers from spreading or even developing in the first place.

    "Nature has already figured out how to prevent cancer, " said Joshua Schiffman, an oncologist at the School of Medicine, University of Utah, US.

    “It's up to us to learn how different animals tackle (处理) the problem so we can use those strategies to prevent cancer in people.”

The Stanford marshmallow (棉花糖) test was originally conducted by psychologist Walter Mischel in the late 1960s. Children aged four to six at a nursery school were placed in a room. A single sugary treat, selected by the child, was placed on a table. Each child was told if they waited for 15 minutes before eating the treat, they would be given a second treat. Then they were left alone in the room. Follow-up studies with the children later in life showed a connect ion between an ability to wait long enough to obtain a second treat and various forms of success.

As adults, we face a version(版本) of the marshmallow test every day. We're not tempted (诱惑) by sugary treats, but by our computers, phones, and tablets — all the devices that connect us to the global delivery system for various types of information that do to us what marshmallows do to preschoolers.

We are tempted by sugary treats because our ancestors lived in a calorie-poor world, and our brains developed a response mechanism(机制) to these treats that reflected their value — a feeling of reward and satisfaction. But as we've reshaped the world around us, dramatically reducing the cost and effort involved in obtaining (获取) calories, we still have the same brains we had thousands of years ago, and this mismatch(不匹配) is at the heart of why so many of us struggle to resist (抵抗) tempting foods that we know we shouldn't eat.

A similar process is at work in our response to information. Our formative (有重大影响的) environment as a species was information-poor, so our brains developed a mechanism that prized (高度重视) new information. But global connectivity has greatly changed our information environment. We are now endlessly bombarded (轰炸) with new information. Therefore, just as we need to be more thoughtful (深思熟虑的) about our caloric consumption (热量消耗), we also need to be more thoughtful about our information consumption, resisting the temptation of the mental "junk food" in order to manage our time most effectively.