Bit by bit, the sand dust that fills the sky is dying down. The blue sky and the burning sun once again hang over the desert.

    He is on the road, driving his beat-up yellow cab. The sides of the road are littered with damaged vehicles. Masses of smoke in the distance tell him that a war is being dragged on throughout his country.

    It's a fine day despite the choking heat. Not a breath of wind is blowing.

    A group of vehicles are traveling towards him, carrying many passengers. The scene reminds him of the market days in this country when crowds of trucks transport folks to the markets; the only difference is, this time, they are not trucks, but tanks, carrying foreigners, guns in hand. He stares at them. They stare back. So they pass by one another.

    “The damned war!” he whispers bitterly. Two days ago, a bomb fell on the market in front of his house, destroying nearly everything in sight. He survived by luck. He decided then and there that he would give up this cab business. This will be his final run. After this, he will leave this place together with his wife and children.

    “Shala and my children, we'll soon meet each other again, after I'm done here.” He turns his head to take a glance at a photo of his wife and children. The glass on the frame is broken, but their smiles in the picture do not fail to provide him with the only comfort that he has.

    Shortly he arrives at a checkpoint. Tanks sit by the side of the road, the sight of which sends a marked coldness through his backbone. A bunch of soldiers armed to the teeth stand by. A foreign soldier signals him to stop. He calms himself down and pulls over. During the past few days, nearly no civilian（平民）vehicles come out of the capital city, his car being the only one on roads.

    A few foreign soldiers come up to him, one, two, three, four, five. The leader bends over to have a look at the old car, then at him. “Where do you come from and where are you going?” With a smile on his face, he answers with a broken speech in the tongue that the soldier can understand, “Sir, I come from the capital. I'm leaving that place because it is a very dangerous place to be, with the war and everything.”

    While talking, he hands a cigarette over to the soldier, then lights it up for him.

    “When will the war end?” he asks.

    “It won't take long. We'll soon give all of you in the capital the true freedom.” The soldier breathes a deep mouthful. He seems to have spotted the photo in the car, “The cigarette is not bad at all. Are those your wife and kids? I have two of my own, roughly the same age.”

    “Oh, yes, they are mine and they are constantly on my mind. They left the city a bit earlier, and I'm on my way to be reunited with them. Perhaps I'm never coming back. Driving a cab around during war times is too dangerous. I'm giving up the business.” He looks at the soldier, still smiling.

    “After we overthrow your dictator(独裁者), you won't have that to worry about. You can come back and pick up your life again.” The soldier is leaning on the door of the car. It is perhaps the first time in many days that he has seen a happy face among the local people. It cheers him up.

    “Maybe, but I have to go to see my family. If you would pay us a visit, my wife will prepare a good meal for all of you. Come with me. This is going to be my last business run and I won't even charge you.”

    “Can't make it. We're on duty. Give our regards to your wife and kids.” The soldier is a bit excited, thinking maybe quite some locals have open arms for them after all. “Oh, yes, I almost forgot. The south is battle-infected. Where is your family?”

    Still smiling, he picks up the broken picture frame, presses a kiss on the photo, then turns around, staring into the eyes of that soldier, not quite himself from excitement, and the other foreign soldiers holding guns. Words drop out of his lips slowly but firmly: “Paradise.”

    Perhaps the last thing he sees is the confused, fearful, twisted expression on the face of that soldier, and the cigarette end dropping from his fingers. Then he pushes the button.

    One of the most recent social changes taking place in the world is social networking. Social networking has been in existence for at least 150 years, and probably longer than that. In the times before the invention of the computer and the World Wide Web (WWW), social networking was done in person. People who had similar likes and interests would gather together to share experiences, make new friends, and improve their businesses.

    On the Internet, social networking websites made their first appearances during the late 1990s. The first major social networking website in the United States was MySpace. MySpace allowed its users to exchange messages, share pictures, and make new friends in a way that was never thought of in the past. With MySpace, people who did not go out much could reach out to others from their own homes.

    In 2004, Facebook was created. It was first a website created for use by Harvard University's students and teachers, but it soon expanded to include just about everyone. It is now larger than some of the largest companies in the world. It is a website that is changing all the time. Facebook has completely changed the way people stay connected with each other and the rest of the world. The way it works is simple. Users can set up a new account (账户) easily. All a new user needs is an email address to start. Once a person has created an account and his friend also has his own Facebook page, he can invite his friend by sending a request out to him. Once you get started, making new friends will come easily.

    Food storing is common in members of the crow（乌鸦）family. A new study tested the birds outside this naturally occurring behaviour, which may have evolved（进化）specifically because it gives crows a survival advantage. Some crow species are known to naturally use tools to recover food. So the researchers tested whether the birds could store and recover a tool so they could get it at their food after a gap of 17 hours—something we wouldn't expect them to do naturally. But they were able to instantly select the tool out of a number of unnecessary items.

    In another experiment, the researchers taught crows to select a token （礼品券）from a number of items so that they could then exchange for food. Again, the birds then showed that they could plan for the future using this new behaviour. This is different from all of the previous studies in future planning, which have focused on naturally occurring behaviour. For example, we know that chimpanzees select, transport and save appropriate tools for future needs.

    These studies have shown that animals can plan for the future—but they left an important question open for debate. Are animals only able to plan to use abilities that have evolved to give them a specific advantage, or can they flexibly and intelligently apply planning behaviour across various actions? Most critics would say the former, as the animals were tested in naturally occurring behaviours.

    But the new research provides the first evidence that animal species can plan for the future using behaviour that doesn't typically occur in nature. This supports the view that at least some recognitive abilities in animals don't evolve just in response to specific problems. Instead, it suggests that animals can apply these behaviours flexibly across problems in a similar way to humans. We need to investigate how flexible behaviour evolved. Then we might be able to see how crows' ability to plan for the future fits in with their broader cognitive powers.

    Australian scientists are trying to give kangaroo-style stomachs to cattle and sheep in order to cut the greenhouse gases they send out, which is thought to be responsible for global warming.

    Thanks to special bacteria in their stomachs, kangaroo flatulence (肠胃气胀) contains no methane and scientists want to transfer that bacteria to cattle and sheep who produce large quantities of the harmful gas.

    While the usual image of greenhouse gas pollution is a billowing smokestack, pushing out carbon dioxide, farm animals' passing wind contribute a surprisingly high percentage of total emissions in some countries.

    “Fourteen percent of emissions from all sources in Australia are from enteric methane from cattle and sheep,” said Athol Klieve, a senior research scientist with the greensland state government. “And if you look at another country such as New Zealand, which has got a much higher agricultural base, they are actually up around 50 percent,” he said.

    Researchers say the bacteria also make the digestive process much more efficient and could potentially save millions of dollars in feed costs for farmers. But it will take researchers at least three years to isolate the bacteria before they can even start to develop a way of transferring it to cattle and sheep.

    Another group of scientists, meanwhile, have suggested Australians should farm fewer cattle and sheep and just eat more kangaroos. And about 20 percent of health-conscious Australians are believed to eat the national symbol already.

    It's low in fat, it's got high protein levels and it is very clean in the sense that basically it is free-range(放养的) animal,” said Peter Ampt of the University of New South Wales' institute of environmental studies.

    When a driver slams on the brakes to avoid hitting a pedestrian crossing the road illegally, she is making a moral decision that shifts risk from the pedestrian to the people in the car. Self-driving cars might soon have to make such ethical (道德的)judgments on their own — but settling on a universal moral code for the vehicles could be a tough task, suggests a survey.

    The largest ever survey of machine ethics, called the Moral Machine, laid out 13 possible situations in which someone's death was unavoidable. Respondents were asked to choose who to spare in situations that involved a mix of variables: young or old, rich or poor, more people or fewer. Within 18 months, the online quiz had recorded 40 million decisions made by people from 233 countries and territories.

    When the researchers analyzed these answers, they found that the nations could be divided into three groups. One contains North America and several European nations where Christianity has been the dominant (占支配地位的)religion; another includes countries such as Japan, Indonesia and Pakistan, with strong Confucian or Islamic traditions. A third group consists of countries in Central and South America, such as Colombia and Brazil. The first group showed a stronger preference for sacrificing older lives to save younger ones than did the second group, for example.

    The researchers also identified relationships between social and economic factors in a country. They found that people from relatively wealthy countries with strong institutions, such as Finland and Japan, more often chose to hit people who stepped into traffic illegally than did respondents in nations with weaker institutions, such as Nigeria or Pakistan.

    People rarely face such moral dilemmas, and some cities question whether the possible situations posed in the online quiz are relevant to the ethical and practical questions surrounding driverless cars. But the researchers argue that the findings reveal cultural differences that governments and makers of self-driving cars must take into account if they want the vehicles to gain public acceptance.

    At least Barbara Wage, who heads a group working on autonomous-vehicle ethics at Audi in Ingolstadt, Germany, says such studies are valuable. Wage argues that self-driving cars would cause fewer accidents, proportionally, than human drivers do each year—but that people might focus more on events involving robots.

    Surveys such as the Moral Machine can help to begin public discussions about these unavoidable accidents that might develop trust. "We need to come up with a social consensus," she says, "about which risks we are willing to take."

A short period of sleep taken during the day is known as a nap. Naps don't just have benefits for adults at work, though. They could also help pupils to make the most of their school day. Studies have shown that a 20 to 30-minute "beauty sleep" makes people more alert and focused. This improves people's ability to remember new information, which would help school children concentrate during lessons. Experts say that napping also improves brain functions, such as memory and the ability to complete difficult tasks.

The school day starts early, which means that pupils don't always get enough sleep because there's no chance to have a lie-in（睡懒觉. Adding naptime during the school day would help exhausted pupils to make up for any sleep they've lost from getting up so early.

There are long-term benefits to taking a short nap, too. According to a recent study from University College London, the brains of people who have regular naps are bigger than those who don't. People's brains naturally shrink (萎缩）when they grow old, and the results showed that little sleeps can help people's brains to age more slowly.

Although a nap can seem like a good idea, going to sleep for too long can actually make you feel worse. It's not very pleasant to wake up from a daytime nap feeling confused and sleepy. Napping during the day can also have a negative impact on how well you sleep at night. This can create a cycle of not being able to sleep well at night, leaving you feeling even more tired in the daytime. Sleep expert Dr Clete Kushida said, "It's generally recommended to maximize(最大化） sleep at night."

Another consideration is that there really isn't time in the school day for pupils to go to sleep. Some parents and teachers are concerned that it would cause children to miss too much lesson time. Pupils might take advantage of the system and use their need for a nap as an excuse to get out of lessons.

So, what do you think? Should school allow kids to have naps, or should you wait until the evening to catch up on your sleep?