Food safety is a problem in all places around the world and people in different areas of the world prepare foods in different ways. The WHO released (发布) five simple rules for preparing food in a safe way. They call these rules the “Five Keys to Safer Food”.

Key 1: Keep clean

    {#blank#}1{#/blank#}People should wash their hands often — before touching food and while they are preparing food. People should wash all surfaces and equipment used for preparing food.

Key 2: Separate raw (生的) and cooked

    Raw foods should not touch prepared foods.{#blank#}2{#/blank#}.

Key 3:{#blank#}3{#/blank#}

    People should cook eggs and meat especially carefully. These foods may carry more micro-organisms (微生物) than other foods. Food like soup must be boiled for at least a minute to make it be cooked completely. It is also important that people re-heat cooked food completely.

Key 4: Keep food at safe temperatures

    When people finish eating, they should keep the left food in a refrigerator below 5℃and shouldn't store it for too long. At room temperature, about 20℃, the amount of micro-organisms can increase very quickly. But temperatures above 60℃ or below 5℃ control the growth of micro-organisms.{#blank#}4{#/blank#}.

Key 5: Use safe water and raw materials

    {#blank#}5{#/blank#}. Damaged or old food may develop harmful chemicals as it gets older.

A. Cook completely

B. This key tells about the importance of washing

C. Eat healthily

D. They can live where we make food

E. People should use safe water and choose fresh foods

F. They cannot grow as quickly in a very hot or very cold environment

G. People should use separate equipment and tools for touching and preparing raw foods

    Here is an astonishing and significant fact: Mental work alone can't make us tired. It sounds absurd. But a few years ago, scientists tried to find out how long the human brain could labor without reaching a stage of fatigue(疲劳). To the amazement of these scientists, they discovered that blood passing through the brain, when it is active, shows no fatigue at all! If we took a drop of blood from a day laborer, we could find it full of fatigue toxins(霉素) and fatigue products. But if we took blood from the brain of an Albert Einstein, it would show no fatigue toxins at the end of the day.

    So far as the brain is concerned, it can work as well and swiftly at the end of eight or even twelve hours of efforts as at the beginning. The brain is totally tireless. So what makes us tired?

    Some scientists declare that most of our fatigue comes from our mental and emotional(情感的) attitudes. One of England's most outstanding scientists, J. A. Hadfield, says, “The greater part of the fatigue from which we suffer is of mental origin. In fact, fatigue of purely physical origin is rare.” Dr. Brill, a famous American scientist, goes even further. He declares, “One hundred percent of the fatigue of a sitting worker in good health is due to emotional problems.”

    What kinds of emotions make sitting workers tired? Joy? Satisfaction? No! A feeling of being bored, anger, anxiety, tenseness, worry, a feeling of not being appreciated—those are the emotions that tire sitting workers. Hard work by itself seldom causes fatigue. We get tired because our emotions produce nervousness in the body.

    Bad news sells.If it bleeds,it leads.No news is good news,and good news is no news.Those are "the classic rules for the evening broadcasts and the morning papers.But now that information is being spread amt monitored（监控）in different ways,researchers are discovering new rules.By tracking people's e-mails and online posts,scientists have found that good news can spread faster and farther than disasters and sob stories.

    "The ‘if it bleeds 'rule works for mass media,"says Jonah Berger,a scholar at the University of Pennsylvania. "They want your eyeballs and don't care how you're feeling.But when you share a story with your friends,you care a lot more how they react.You don't want them to think of you as a Debbie Downer."

    Researchers analyzing word-of-mouth communication—e-mails,Web posts and reviews,face-to-face conversations—found that it tended to be more positive than negative,but that didn't necessarily mean people preferred positive news.Was positive news shared more often simply because people experienced more good things than bad things?To test for that possibility,Dr.Berger looked at how people spread a particular set of news stories: thousands of articles on The New York Times' website.He and a Penn colleague analyzed the "most e-mailed" list for six months.One of his first findings was that articles in the science section were much more likely to make the list than non-science articles.He found that science amazed Times' readers and made them want to share this positive feeling with others.

    Readers also tended to share articles that were exciting or funny,or that inspired negative feelings like anger or anxiety,but not articles that left them merely sad.They needed to be aroused（激发）one way or the other,and they preferred good news to bad.The more positive an article,the more likely it was to be shared as Dr.Berger explains in his new book,"Contagious: Why Things Catch On."

    Are you interested in students in other countries: Do they also have so much homework like you? What do they do in their spare time?

    On April 8,a report came out on the lives of high school students in China,Japan,South Korea and the US.It surveyed（调查）around 6,200 students from the four countries last year.You will find the answers to many of your questions in this report.

    Who study hardest?

    Chinese students spend the most time studying.Nearly half of Chinese students(48.6%) spend more than two hours on their homework every day.That's much more than students of the US(26.4%),Japan(8.2%) and South Korea (5.2%).

    Who sleep most often in class?

    Japanese students fall asleep in class most often.About 45% of them said they sometimes sleep in class.In South Korea, it's 32%;in the US,21%;and 5% in China.

    Who are the most distracted（分心的）?

American students are the most active in class,but also the most distracted.64.2% said they chat with friends in class;46.9% said they eat snacks in class;and 38.9% said they send emails or read storybooks in class.

    What do they do after school?

    In their spare time, most Chinese students study or surf the Internet.Most American students go out to play with their friends.Most Japanese students do physical exercises.Most Korean students watch TV.

    There is a breakthrough in building aircrafts. Bendable wings covered with overlapping(部分重叠) pieces resembling fish sizes could be used to build swifter, fuel-efficient aircraft, a new study finds.

    Nowadays, conventional aircrafts typically rely on ailerons (副翼) to help control the way the planes tip as they fly. However, when the Wright brothers flew the first airplane, Flyer 1, over a century ago, they used no ailerons but wires and pulleys that twisted the wood-and-canvas wings, to control the plane.

    Scientists have long sought to develop aircrafts that can alter their wings during flight, just as birds can. However, most previous attempts have failed because they relied on heavy mechanical control structures within the wings. These structures were also complex and unreliable, said Neil Gershenfeld, a physicist and director of the Center for Bits and Atoms at Massachusetts Institute of Technology (MIT).

    The new wing consists of a system of tiny, strong, lightweight modules. The shape of the wing can be changed uniformly along its length using two small motors, which apply a twisting pressure to each wingtip. These wings are covered in “skins” of overlapping strips of flexible material resembling fish sizes. These strips move across each other as the wings alter, providing a smooth outer surface, the researchers explained.

    Wind-tunnel tests of these wings showed that they at least matched the aerodynamic properties of conventional wings, at about one-tenth the weight. Initial tests using remotely piloted aircrafts made with these wings have shown great promise, said Benjamin Jenett, a graduate student at the Center for Bits and Atoms at MIT.

    The new modular structures the scientists developed could be manufactured quickly in mass quantities and then installed by teams of small robots. These modular structures also can be disassembled more easily, making repairs simpler.

    “Still, the first aircraft built using this strategy will not be a passenger jet, ”Gershenfeld said. “Instead, the technology will likely first be tested on unmanned aircraft, leading to drones (无人机) that can fly for a long time, to help deliver internet access or medicine to remote villages and do some rescue works.”

    Generations of children grew up reading comic(漫画) books secretly, hiding out from parents and teachers who saw them as a waste of time and a risk to young minds. Comics are now gaining a new respectability at school. That is thanks to an increasingly popular and creative programme, often aimed at struggling readers, that encourages children to plot, write and draw comic books, in many cases using themes from their own lives.

    The Comic Book Project was started in 2001 by Michael Bitz at an elementary school in Queens. Since its creation, the programme, which is mainly conducted after school, has spread to more than 850 schools across the country. It has gotten a big push from the craze(狂热) among adolescents for comic book clubs and for Manga, a widly popular variety of comic originating in Japan.

    The point is not to drop a comic book on a child's desk and say “read this”. Rather, the workshops give groups of students the opportunity to collaborate(合著) on often complex stories and charac-ters that they then revise, publish and share with others in their communities.

    Teachers are finding it easier to teach writing, grammar and punctuation with material that students are fully invested in(投入). And it turns out that comic books have other built-in advantages. The pairing of visual and written plotlines that they rely on appear to be especially helpful to struggling readers. No one is suggesting that comic books should substitute for traditional books or for standard reading and composition lessons. Teachers who would once have dismissed comics out of hand are learning to exploit(利用) a style that clearly has a powerful hold on young minds. They are using what works.