Sure, you talk to your parents, but what if you need to really talk? Maybe you have a problem you can't solve alone, or it could be that you want to feel closer to Mom and Dad.

    It's easy to say" Hi, Mom" or "Dad, can you pass the potatoes?", but it can be harder to start a discussion about tougher topics. When you were younger, it probably felt easy to tell your parents about your trouble. Even though you're older now, it's still perfectly OK to believe in your parents. In fact, it can help a lot.

    So why does it seem so uncomfortable at times? Why is it hard to bring up the important stuff? Sometimes kids don't speak up because they don't want to feel embarrassed. Let's face it—talking about personal stuff can make you feel embarrassed. But remember, your parents know you pretty well, and they were your age once, too! So don't let a little embarrassment stop you. It's OK to go ahead and share the personal stuff.

    Other times, kids might not want to make their parents anxious or upset. As you explain your problem, your mom might look sad or your dad might look worried. But that's OK. Your mom and dad can deal with knowing about your problem, big or small. That look on their face just means they care, and they feel for you. That's what families do—we feel for the people we love.

    Sometimes, kids don't bring up a problem because they just don't want to think about it. They hope it will just go away. When meeting a problem, they will likely choose not to face it or just keep it for themselves. But running away from a problem hardly ever solves it. And bottling up your feelings can make you feel stressed.

    Talking things over with a parent can help you feel less stressed. Together, you can think of ways to solve the problem and make you feel better. Just knowing your parent understands and cares about what you're going through can reduce your stress a lot.

    Most academics would view a post at an elite university like Oxford or Harvard as the crowning achievement of a career—bringing both honour and access to better wine cellars. But scholars desire such places for reasons beyond glory. They believe perching on one of the topmost branches of the academic tree will also improve the quality of their work, by bringing them together with other geniuses with whom they can collaborate and who may help spark new ideas. This sounds reasonable. Unfortunately，as Albert Laszlo Barabasi of Northeastern University，in Boston (and also, it must be said, of Harvard), shows in a study published in Scientific Reports, it is not true.

    Dr Barabasi and his team examined the careers of physicists who began publishing between 1950 and 1980 and continued to do so for at least 20 years. They ranked the impact of the institutions these people attended by counting the number of citations each institution's papers received within five years of publication. By tracking the association of individual physicists and counting their citations in a similar way, Dr Barabasi was able to work out whether moving from a low to a high-ranking university improved a physicist's impact. In total, he and his team analysed 2,725 careers.

    They found that, though an average physicist moved once or twice during his career, moving from a low-rank university to an elite one did not increase his scientific impact. Going in the opposite direction, however, did have a small negative influence. The consequence is that elite university do not，at least as far as physicists are concerned，add value to output. That surprising conclusion is one which the authorities in countries such as Britain, who are seeking to concentrate expensive subjects such as physics in fewer, more elite institutions—partly to save money, but also to create what are seen as centers of excellence—might wish to consider.

    As computers become more popular in China, Chinese people are more and more depending on computer keyboards to input Chinese characters(汉字). But if they use the computer too much, they may end up forgetting the exact strokes(笔画) of each Chinese character when writing on paper. Experts suggest people, especially students, write by hand more.

    Do you write by hand more or type more? In Beijing, students start using a computer as early as primary school. And computer dependence is more widely spread among university students. Almost all their homework and essays are typed on a computer.

    All the students interviewed say they usually use a computer.

    It's faster and easier to correct if using a computer. And that's why computers are being used more and more often to modern education. But when people are taking stock in computers increasingly, problems appear.

    'When I'm writing with a pen, I find I often can't remember how to write a character, though I feel I'm familiar with it.'

    'I'm not in the mood to write when faced with a pen and paper.'

    Many students don't feel this is something to worry about. Now that it's more convenient and efficient to write on a computer, why bother to handwrite?

    Many educators think differently. Shi Liwei, headmaster of a famous primary school in the capital said, 'Chinese characters enjoy both practical and aesthetic (审美的)value. But those characters typed with computer keyboards only keep their practical value. All the artistic beauty of the characters is lost. And handwriting contains the writer's feelings. Through one's handwriting, people can get to know one's thinking and personality. Beautiful writing will give people a better first impression of them.'

    To encourage students to handwrite more, many primary schools in Beijing have made writing classes compulsory（必修的）and in universities, some professors are asking students to turn in their homework and essays written by hand.

    Water is a necessity of life. Rain, especially, helps plants grow and stay green. But too much rain, especially in cities, can lead to flooding. That can cause waste water systems to overflow and send pollutants into rivers and other waterways. To fight the problem, several cities in the United States are starting programs like rooftop gardens.

    A team at the University of the District of Columbia in the nation's capital has created a garden on the top of one school building. The garden holds many kinds of plants to help absorb rainwater and grow food at the same time. Architect David Bell has designed five "green roofs" for the university. He says he is excited about the project because "it meant doing something more than just dealing with storm water management. It took advantage of a resource above the city and these flat roofs that aren't doing anything really became something that was about urban agriculture." Rainwater is collected in large containers and sent through a system that waters the rooftop garden. The roof is filled with green life that appeals to insects.

    In cities, "you don't have that many spaces to choose from and so rooftops are just (unused) space," says Caitlin Arlotta. She is a student in the school's Urban Agriculture program. The project is part of a research program to see which plants do well on rooftops. The researchers are looking at plants including strawberries, tomatoes and sweet potatoes. The university also has other green spaces. "We also have our own farm experiments," Arlotta said. "Within each of those growing systems, we want to be able to tell people which sorts of these crops grow the best."

    Sandy Farber Bandier helps run UDC's Master Gardener program. It seeks to improve cities and make them beautiful by training people to become Master Gardeners. She says she's been surprised by the garden's output. "My biggest surprise was that we produced 4, 250 pounds of produce the first year and was able to spread that to people in need." She also likes being able to show people who live in D. C. and others beyond the nation's capital what and how food can be grown on a rooftop. "This is the future for food. You grow it here, you prepare it in a commercial kitchen, you distribute through farmers markets, food trucks, and then you recycle."

Crocodiles today look very similar to ones from 200 million years ago. There are also very few species alive today—just 25. Other animals such as lizards (蜥蜴) and birds have achieved a diversity of many thousands of species in the same amount of time or less.

Prehistory also saw types of crocodile we don't see today, including giants as big as dinosaurs, plant-eaters, fast runners and snake-like forms that lived in the sea. The rate of their evolution is generally slow, but occasionally they evolve more quickly because the environment has changed. In particular, their evolution speeds up when the climate is warmer, and their body size increases.

The body size of crocodiles is important because it interacts with how fast animals grow, how much food they need, how big their populations are and how likely they are to become extinct. The limited diversity of crocodiles and their apparent lack of evolution is a result of a slow evolutionary rate. It seems the crocodiles arrived at a body plan that was very efficient and perfect enough that they didn't need to change it in order to survive. This perfection could be one explanation why crocodiles survived Cretaceous period (白垩纪), in which the dinosaurs died out.

Crocodiles generally develop better in warm conditions because they cannot control their body temperature and require warmth from the environment. The climate during the age of dinosaurs was warmer than it is today, and that may explain why there were many more varieties of crocodiles than we see now. Being able to draw energy from the sun means they do not need to eat as much as a warm-blooded animal like a bird or a mammal (哺乳动物).