Grown-ups are often surprised by how well they remember something they learned as children but have never practiced ever since. A man who has not had a chance to go swimming for years can still swim as well as even when he gets back in the water. He can get on a bicycle after many years and still ride away. He can play catch and hit a ball as well as his son. A mother who has not thought about the words for years can teach her daughter the poem that begins "Twinkle, twinkle, little star" or remember the story of Cinderella or Goldilocks and the Three Bears.

    One explanation is the law of overlearning, which can be stated as follows: Once we have learned something, additional learning trials(尝试) increase the length of time we will remember it.

    In childhood we usually continue to practice such skills as swimming, bicycle riding, and playing baseball long after we have learned them. We continue to listen to and remind ourselves of words such as "Twinkle, twinkle, little star" and childhood tales such as Cinderella and Goldilocks. We not only learn but overlearn.

    The multiplication tables(乘法口诀表) are an exception(例外) to the general rule that we forget rather quickly the things that we learn in school, because they are another of the things we overlearn in childhood.

    The law of overlearning explains why cramming(突击学习)for an examination, though it may result in a passing grade, is not a satisfactory way to learn a college course. By cramming, a student may learn the subject well enough to get by on the examination, but he is likely soon to forget almost everything he learned. A little overlearning, on the other hand, is really necessary for one's future development.

    "I'm the smartest kid in class." We all want our kids to be self-confident, but unrealistic perception(认知) of their academic abilities, a new study finds, damage a child's relationship with others in the classroom: The more one student feels unrealistically superior(更好的) to another, the less the two students like each other.

Katrin Rentzsch of Bamberg University in Germany first became interested in the effects of such self-perception when she was studying how people became labeled as nerds(书呆子). "I really got interested in the question of whether it's OK to boast(吹嘘) about achievements," she says.

    This line of thinking led her towards something psychologists call "self-enhancement" －when a person feels unrealistically superior to someone else. So Rentzsch and her colleague Michela Schroder-Abe decided to take a closer look at how such self-enhancement affects relationships, so they turned to the eighth-grade classroom, somewhere they could measure differences between actual academic performance, and social popularity. The 358 students came from 20 eighth-grade classes in schools in southeast Germany.

    The researchers asked each student to rate their classmates, in terms of their likability and of their feelings of academic superiority. They then compared those ratings with the students' grades in math, physics, German and English. Importantly, they conducted the analysis at two different social levels: "habitual"－the way people act in general, and "relationship"－the way someone acts around a specific individual.

    In future work, Rentzsch would like to look at these effects on adults, perhaps specifically in team work. She's also interested in self-enhancement beyond academic achievements, for example physical attractiveness. And another question to explore is why students overestimate their academic abilities. Perhaps it is because of too much praise from their parents or teachers.

    Every man dreams of having agood car. With luxury cars, like Bentley, Lamborghini and Rolls-Royce, going intothe world of SUVs, if you have deep pockets, you will be spoilt for choice.

    ◆Lamborghini Aventador SVJ

    Using a new aerodynamic system allows it toset a car lap record of 6: 44 97 at Nurburgring, one of the longest and most challengingcircuits in the world. Plus, carbon fiber can be seen everywhere, which makes thecar strong and lightweight. There're only 900 being built and you'llneed to coughup $517, 770 to buy one.

    ◆Aston Martin DBX

    The DBX is Aston Martin's maiden SUVproduct. It features a choice of two gas engines—a 4.0-liter V8 from Mercedes anda 5.2-liter V12 from its own. The price is predicted to be around $250, 000.

    ◆Audi E-tron

    Being an eco-friendly motoring, it is an all-electricSUV that makes up for its rather ordinary appearance with design, luxury and technology.At the front and back are electric motors which insure progress is rapid. In additionto plenty of storage space, the Audi E-tron provides side cameras instead of sidemirrors and air suspension that adapts to the terrain (地形). Hand over $74, 800 and it's yours.

    ◆Tesla Roadster

    Tesla Roadster will turn most heads, Zero to60 in 1.9 seconds means it will leave most cars for dust. The top speed is 250 mph,which is also unheard of for most cars—let alone an all-electric one. Having advancedautonomous driving systems and a huge touchscreen for surfing the Internet, it won'tmake you regret for paying $200, 000.

    The cold and icy land that is the Eskimo's home is a dangerous one. The Eskimo once believed that to be safe from danger he had to obey taboos(禁忌). Taboos were rules that told him what he must do and must not do.

    The Eskimo had taboos connected with almost everything he did. He had to keep them in mind at all times. He believed that to break one would bring disaster. For the Eskimo, it was taboo to store reindeer(驯鹿) and seal (海豹) meat together. He could not even eat them on the same day. He believed the Goddess Sedna had separated the land animals from the sea animals. He thought bringing them together would cause the hunting to be bad.

    There were other taboos concerning animals. When a dead seal was brought into the house, the women had to stop working. They had to give its spirit a drink of water. If they did not, the spirit would be angered. It would keep other animals from being caught.

    When the Eskimo broken a taboo, he believed a black cloud formed around his head. He had to tell the others in the village what he had done. He thought that if he did not tell his neighbors, they would catch the black cloud. Then the whole village would have bad luck.

Robots have long been drawing inspiration from animals, with the creation of robot dogs or snake-shaped robots. And yet, the field of robotics is far less enthusiastic about the other kind of living things—plants. Barbara Mazzolai, an Italian roboticist owes this to a misconception about plant behavior: that they cannot move or think. "It's not true at all," she says. To challenge this view, Dr Mazzolai and her team recently launched a machine called "FiloBot", a robot based on a climbing species.

To survive, a climbing plant must switch between several different behaviors. In forest environments, it must first grow out of the soil and travel along the ground in search of a support to hold onto, such as a nearby tree. Once a support is located, though, the plant fixes itself around the object and then growing towards the light. To choose the best angle to grow upwards, a climbing plant uses its shoots(芽) to receive information about light and gravity.

FiloBot has sensors on its main shoot. It can 3D-print its body with plastic and grow at a controllable rate. These functions researchers found, enabled FiloBot to cross gaps, and find things to attach to. The lack of heavy on-board computing device means that it is light and requires minimal care, while its slow pace means that it doesn't disturb things around it, making it possible to move through a complex, unseen environment, or monitoring disaster sites.

For now, FiloBot is still being tested. Its tendrils(卷须) have not left the laboratory. Still, it has already been employed in deconstructing plant behaviour. For example, it was long assumed that climbing plants find their supports by growing towards shade, though the exact mechanism was unclear. FiloBot could imitate this behaviour by detecting far-red light, which is typical of shaded areas, providing clues to how plants do it.

Dr Mazzolai hopes that such projects will inspire other roboticists to take their cues from plants and develop completely new technologies.

Taiwan was once known as "Garbage Island". Now it is a word leader which recycles more than half of its waste in business that brings in over $2 billion a year.

In 1993, Taiwan was filled with garbage. There was almost no recycling. Two thirds of its landfills were full. Around 20% of the island's garbage was dumped (丢弃). The rest was either buried in a landfill, or burned, leaving the island in an unpleasant and unhealthy situation.

In 1998, the government took action. Their plan affected companies that made products or brought them into Taiwan. These companies were required to take care of their own waste, or to pay the government to do it. The government used the money it collected to improve recycling in the area. Taiwan gave away as much as $6 billion a year to help recycling companies.

Ordinary people had apart, too. The government created a plan called Pay As You Throw. People were required to separate their waste into two groups-garbage, and things that are recyclable or reusable. Recycling is free, but people have to buy special blue bags to throw things away. People quickly began to recycle more.

The government also made it easy for people to deal with their waste. Yellow garbage trucks come around often. To let people know they're coming, they play music. People can also track (追踪) the garbage trucks by using a smartphone app.