The American believe that anybody can become President of the United States. In a recent Hollyhood comedy(喜剧), 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(典型的) 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 appearance. 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(经典).

    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!

    Women are friendly．But men are more competitive．Why? Researchers have found it's all down to the hormone oxytocin （荷尔蒙催生素）．Although known as the love hormone, it affects the sexes differently．

"Women tend to be social in their behavior．They often share with others．But men lend to be competitive．They are trying to improve their social status," said Professor Ryan．

    Generally, people believe that the hormone oxytocin is let out in our body in various social situations and our body creates a large amount of it during positive social interactions （互动） such as falling in love or giving birth．

But in a previous experiment Professor Ryan found that the hormone is also let out in our body during negative social interactions such as envy．

    Further researches showed that in men the hormone oxytocin improves the ability to recognize competitive relationships, but in women it raises the ability to recognize friendship．

Professor Ryan's recent experiment used 62 men and women aged 20 to 37．Half of the participants（参与者）received oxytocin．The other half received placebo （安慰剂）．

    After a week, the two groups switched with participants．They went through the same procedure with the other material．

    Following each treatment, they were shown some video pictures with different social interactions．Then they were asked to analyze the relationships by answering some questions．The questions were about telling friendship from competition．And their answers should be based on gestures, body language and facial expressions．

    The results indicated that, after treatment with oxytocin, men's ability to correctly recognize competitive relationships improved, but in women it was the ability to correctly recognize friendship that got better．

    Professor Ryan thus concluded: "Our experiment proves that the hormone oxytocin can raise people's abilities to better distinguish different social interactions．And the behavior differences between men and women are caused by biological factors （因素） that are mainly hormonal．"

    The fence was long and high. He put the brush into the whitewash and moved it along the top of the fence. He repeated the operation. He felt he could not continue and sat down.

    He knew that his friends would arrive soon with all kinds of interesting plans for the day.

    They would walk past him and laugh. They would make jokes about his having to work on a beautiful summer Saturday. The thought burned him like fire.

    He put his hand into his pockets and took out all that he owned. Perhaps he could find some way to pay someone to do the whitewashing for him. But there was nothing of value in his pockets—nothing that could buy even half an hour of freedom. So he put the bits of toys back into his pockets and gave up the idea.

    At this dark and hopeless moment, a wonderful idea came to him. It filled his mind with a great, bright light. Calmly he picked up the brush and started again to whitewash.

    While Tom was working, Ben Rogers appeared. Ben was eating an apple as he walked along the street. As he walked along it, he was making noises like the sound of a riverboat. First he shouted loudly, like a boat captain. Then he said “Ding－Dong－Dong”,“Ding－Dong－Dong” again and again, like the bell of a riverboat. And he made other strange noises. When he came close to Tom, he stopped.

    Tom went on whitewashing. He did not look at Ben. Ben stared a moment and then said: “Hello! I'm going swimming, but you can't go, can you？”

    No answer. Tom moved his brush carefully along the fence and looked at the result with the eye of an artist. Ben came nearer. Tom's mouth watered for the apple, but he kept on working.

    Ben said, “Hello, old fellow, you've got to work, hey？”

    Tom turned suddenly and said, “Why, it's you, Ben! I wasn't noticing.”

     “Say—I'm going swimming. Don't you wish you could? But of course you'd rather work—wouldn't you? Of course you would.”

    Tom looked at the boy a bit, and said, “What do you call work？”

     “Why, isn't that work？”

    Tom went back to his whitewashing, and answered carelessly.

     “Well, maybe it is, and maybe it isn't. All I know is, it suits Tom Sawyer.”

     “Oh come, now, you don't mean to say that you like it？”

    The brush continued to move.

     “Like it? Well, I don't see why I shouldn't like it. Does a boy get a chance to whitewash a fence every day？”

    Ben stopped eating his apple. Tom moved his brush back and forth, stepped back to look at the result, added a touch here and there, and stepped back again. Ben watched every move and got more and more interested. Soon he said，“Say, Tom, let me whitewash a little.”

    Tom thought for a moment, and was about to agree, but he changed his mind.

     “No—no—it won't do, Ben. You see, Aunt Polly wants this fence to be perfect. It has got to be done very carefully. I don't think there is one boy in a thousand, maybe two thousand, that can do it well enough.”

     “No—is that so? Oh come, now—let me just try. Only just a little.”

“Ben, I'd like to, but if it isn't done right, I'm afraid Aunt Polly ”

     “Oh, I'll be careful. Now let me try. Say—I'll give you the core of my apple.”

     “Well, here—No, Ben, now don't. I'm afraid …”

     “I'll give you all of it.”

    Tom gave up the brush with unwillingness on his face, but joy in his heart. And while Ben worked at the fence in the hot sun, Tom sat under a tree, eating the apple, and planning how to get more help. There were enough boys. Each one came to laugh, but remained to whitewash. By the time Ben was tired, Tom sold the next chance to Billy for a kite; and when Billy was tired, Johnny bought it for a dead rat—and so on, hour after hour. And when the middle of the afternoon came, Tom had won many treasures.

    And he had not worked. He had had a nice idle time all the time, with plenty of company, and the fence had been whitewashed three times. If he hadn't run out of whitewash, Tom would have owned everything belonging to his friends.

    He had discovered a great law of human action, namely, that in order to make a man or a boy want a thing, it is only necessary to make the thing difficult to get.

    We know that our pet dogs and cats can recognize our faces, but our pet fish? A team of scientists from the UK and Australia have discovered that archer-fish(喷水鱼) can distinguish human faces!

    This marks the first time that a species of fish has shown such an ability. Such abilities have been previously shown in birds, but unlike fish, they have been proven to possess structures similar to the neocortex(大脑新皮层), the researchers added.

    "Being able to distinguish between a large number of human faces is a surprisingly difficult task," Dr Newport said, "mainly due to the fact that all human faces share the same basic features."

    During their experiments, Dr Newport and her colleagues presented archerfish with two images of human faces, and trained them to choose one by spitting jets(喷射流)of water at that picture. Next, the fish were presented with the familiar face and several that were unfamiliar, and were able to correctly pick the one that they had been trained to recognize, even when features such as head shape and color were removed from the selected pictures.

    In the first experiment, the archerfish were tasked with picking the previously learned face from a group of 44 new ones, which they did with 81 percent accuracy. In the second, the researchers decided to make things a little harder. They took the pictures and made them black and white and evened out (使平均) the head shapes. You would think that would throw the fish for a loop. But no, they were able to pick the familiar face even then—and with more accuracy: 86%!

    "Fish have a simpler brain than humans and entirely lack the section of the brain that humans use for recognizing faces. Despite this, fish may still be capable of finding the face they are trained to recognize," Dr Newport said. "The fact that archerfish can learn this task suggests that complicated brains are not necessarily needed to recognize human faces."

    Forty-three years ago, a man took a "small step" on the moon and brought mankind a "giant leap" forward. As the first person to walk on the moon, American astronaut Neil Armstrong is a man whose name will be remembered for generations to come.

    But being the first is never easy. With so many unknowns about space at that time, Armstrong himself was astonished that Apollo 11 actually worked. He thought he and his partners had merely a 50 percent chance of a successful landing back in 1969.

    It was tough indeed. When the module (登月舱) was approaching the moon's surface, the computer wanted to rest them on a steep slope covered with rocks, but Armstrong realized it was an unsafe place to stop.

    As a last minute decision, he safely landed the module by himself. When they finally touched the ground, "there was something like 20 seconds of fuel left," he said in an interview earlier this year.

    Unfortunately, some people doubted his visit to the moon, saying it was faked. But Armstrong responded with a chuckle (轻声笑), saying: "It was never a concern to me because I knew one day, somebody was going to go fly back up there and pick up that camera I left."

    For all his global fame, Neil Armstrong is a remarkably modest man. He rarely gave interviews and didn't like talking about his achievement. He stopped giving his signatures when he found that people sold them for thousands of dollars.

    "I guess we all like to be recognized not for one piece of fireworks but for the ledger (记账簿) of our daily work," Armstrong said in a CBS interview in 2005. When asked how he felt knowing his footprints would be likely to stay on the moon's surface for thousands of years, he said: "I kind of hope that somebody goes up there one of these days and cleans them up."

    Armstrong passed away last month at the age of 82, but he will be memorized. "The next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink (眨眼示意)," his family said to Reuters.

Gorman is the youngest poet in U. S. history. She became the youth poet laureate (获奖者) of Los Angeles at age 16 in 2014 and the first national youth poet laureate three years later. She has recently completed her studies at Harvard University.

Her mother, Joan Wicks, teaches middle school in Watts. Shuttling among the neighborhoods gave Gorman a window to the world. Her like for poetry dates at least back to the third grade when her teacher read Ray Bradbury's Dandelion Wine to the class.

Gorman is a lot better at it now, but still working on her confidence as a public speaker. "Until two or maybe three years ago, I couldn't say the letter 'r'. Even to this day sometimes I struggle with it. I'd want to say 'girls can change the world', but I can not say so many letters in that statement, so I'd say things like 'young women can shape the globe'."

For Gorman, writing became a cure. "I used writing as a form of self expression to get my word on the page. So the more I recited out loud, the more I was able to teach myself how to pronounce these letters which for so long had been my greatest impediment." Gorman said she also used a song from Miranda's Pulitzer Prize-winning Broadway musical Hamilton to help with her speaking. "But I don't look at my disability as a weakness," said Gorman. "It's made me the performer that I am and the storyteller that I strive to be."

In September, Gorman will release Change Sings, the first of two children's books. The poet says she desires to publish a book "in which kids could see themselves as change-makers in history, rather than just observers".