The African elephant, the largest land animal remaining on earth , is of great importance to African ecosystem(生态系统). Unlike other animals, the African elephant is to a great extent the builder of its environment. As a big plant-eater, it largely shapes the forest-and-savanna(大草原)surroundings in which it lives, therefore setting the terms of existence for millions of other animals that live in its habitat(栖息地).

    It is the elephant's great desire for food that makes it a disturber of the environment and an important builder of its habitat. In its continuous search for the 300 pounds of plants it must have every day, it kills small trees and underbushes, and pulls branches off big trees. This results in numerous open spaces in both deep tropical forests and in the woodlands that cover part of the African savannas. In these open spaces are numerous plants in various stages of growth that attract a variety of other plant-eaters.

    Take the rain forests for example. In their natural state, the spreading branches overhead shut out sunlight and prevent the growth of plants on the forest floor. By pulling down trees and eating plants, elephants make open spaces, allowing new plants to grow on the forest floor. In such situations, the forests become suitable for large hoofed plant-eaters to move around and for small plant-eaters to get their food as well.

    What worries scientists now is that the African elephant has become an endangered species. If the elephant disappears, scientists say, many other animals will also disappear from vast areas of forest and savanna, greatly changing and worsening the whole ecosystem.

    The forest in Senegal, a country in western Africa, is full of the chimps' usual noises. Suddenly dogs bark. Larger male chimps drop from the trees to face the threat while the others climb to safety. Then the dogs' young human masters appear.

One mother chimp with a tiny baby tries to run. The dogs attack and separate them. The two teenage boys quickly catch the baby chimp. But they don't act out of sympathy — they save the baby so they can sell it.

    After the teenagers return to their hometown, they visit a man who is said to be very interested in chimps. When they ask the man, Johnny Kante, if he wants to buy the baby, he replies, “That's not what we do.” Kante is a member of a scientific team. Although Kante is angry with the teens for capturing the chimp, he hides his anger and persuades them to take him to the baby chimp.

    Unsure of what to do next upon seeing the chimp, Kante calls Jill Pruetz, the head of the chimp research team. “I'm really worried,” says Pruetz, doubtful that the mother is still alive. But knowing that wild chimps sometimes adopt orphans（孤儿）， Kante and pruetz decide they must try to return the baby chimp to its wild community.

    Kante pays another visit to the teenagers. After he explains how much trouble they are in, because chimps are an endangered species, he requests they should give him the frightened baby without payment. They agree. Kante takes the baby chimp to his home and feeds her milk from a bottle whenever she cries.

    The next morning, Pruetz and Kante leave the baby with another team member and begin their search for the wild chimps. Pruetz quickly finds the group in the woods. She recognizes the female that is without her child.

    Pruetz is so excited that she runs the entire mile back to bring the baby chimp to the tree where the chimps are hanging out. The researchers place the baby on the ground near the tree and back away. Almost immediately, a male chimp drops to the ground and stares at the baby curiously. He carries her back to where the mother is waiting.

    Pruetz still can't believe how fortunate they were to have reunited the mother and child. “Surprising is the only word I can think of,” she says.

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    People can be addicted to different things, e.g. alcohol, drugs, certain foods, or even television. People who have such an addiction are compulsive, i.e they have a very powerful psychological need that they feel they must satisfy. According to psychologists, many people are compulsive spenders; they feel that they must spend money. This compulsion, like most others, is irrational-impossible to explain reasonably. For compulsive spenders who buy on credit, charge accounts are even more exciting than money. In other words, compulsive spenders feel that with credit, they can do anything. Their pleasure in spending enormous amounts is actually greater than the pleasures that they get from the things they buy.

    There is even a special psychology of bargain hunting. To save money, of course, most people look for sales, low prices, and discounts. Compulsive bargain hunters, however, often buy things that they don't need just because they are cheap. They want to believe that they are helping their budgets, but they are really playing an exciting game: when they can buy something for less than other people, they feel that they are winning. Most people, experts claim, have two reasons for their behavior: a good reason for the things that they do and the real reason.

    It is not only scientists, of course, who understand the psychology of spending habits, but also business people. Stores, companies and advertisers use psychology to increase business: they consider people's need for love, power, or influence, their basic values, their beliefs and opinions, and so on in their advertising and sales methods.

    Psychologists often use a method called “behavior therapy” to help individuals solve their personal problems. In the same was, they can help people who feel that they have problems with money.

    Google, hoping to put down a protest by employees upset that the technology they were working on could be used for deadly purposes, will not renew a contract with the Pentagon(五角大楼) for artificial intelligence work when a current deal expires next year.

    Diane Greene, who is the head of the Google Cloud business that won a contract with the Pentagon's Project Maven, said during a weekly meeting with employees Friday that the company was backing away from its AI work with the military, according to a person familiar with the discussion but not permitted to speak publicly about it.

    Google's work with the Defense Department on the Maven program, which uses artificial intelligence to interpret video images and could be used to improve the targeting of drone strikes, riled the internet giant's workforce.

    About 4,000 Google employees signed a petition(请愿书) demanding "a clear policy stating that neither Google nor its contractors will ever build warfare technology," and a handful of employees resigned in protest.

    The money for Google in the Project Maven contract was never large by the standards of a company with profit of $110 billion last year — $9 million, one official told employees, or a possible $15 million over 18 months, according to an internal email.

    But some company officials saw it as an opening to much greater revenue down the road. In an email last September, a Google official in Washington told colleagues she expected Maven to grow into a $250 million-a-year project, and eventually it could have helped open the door to contracts worth far more.

    Liana nervously bit her nails while she waited for the exam to arrive. She looked around the room; hundreds of other law students sat in rows staring anxiously at the tables in front of them. Just as she began to take a deep breath to calm her anxiety, an exam booklet(册子) was placed in front of her. This was the moment she had been expecting ever since she began law school three years ago. She picked up her pencil, and opened to the first page of the bar exam, a test for all students wanting to become licensed lawyers.

    Liana never thought she would want to become a lawyer. Her parents were both artists. Law was something she had not been exposed to as a child. But art made for a tumultuous career—both of her parents had struggled to find jobs and worked round the clock when they were young. Even though they finally seemed successful and happy, Liana wanted something different.

    She was the anchor on her high school debate team, and consistently impressed her competitors with her analytical thinking. "Never argue with Ms. Lakes," her teachers would say. So she chose to major in law. In her mind, she pictured herself in a New York City courtroom(法庭) dressed in an expensive suit, with papers in her hand, waving at the jury(陪审团) in a speech on human rights.

    But now, with the bar exam sitting in front of her, she started to worry. "What if I don't pass? Did I study enough?" Her thoughts raced through her mind. On the first page were seven paragraphs detailing a law situation followed by a series of questions. Liana read through the paragraphs, and quickly scribbled down an explanation of the first question before moving onto the next question. The next few hours went like this as the clock ticked closer and closer to the lunch hour.

    At 12:00 p.m. sharp, a buzzer(蜂鸣器) sounded and everyone was told to put down their pencils and walked out for an hour-long lunch break. At lunch, Liana met her friend, Kevin.

    "How did it go?" she asked. "To be honest, I've no idea. I just kept writing." Kevin said. Liana laughed and said she felt the same way.

    After lunch, the two exchanged words of encouragement. They strolled back into the exam center a bit more refreshed. Liana finished the second half of the exam that day with a better feeling than what she started with in the morning.

Recess (课间休息) time has been dropping for many children in America. This drop began the same year the No Child Left Behind Act (NCLB) was passed. The law aimed to make American education system more internationally competitive by introducing achievement goals for schools. And the goals are gauged (评定) by standardized tests in reading and math. If schools missed their achievement goals, they could be in trouble, including loss of funding.

It's no surprise that teachers have felt the pressure to make sure students perform well on standardized tests. When educators are facing pay cuts, loss of funding to their school and perhaps even the loss of their jobs, it's no wonder that they started questioning if recess was a waste of time. This pressure to bring even more learning into the school day is especially felt by underperforming, low-income schools that are already short of funding.

It may seem strange to send kids out to play when they're falling below state standards, but getting outside for unstructured (散乱的) play may be more helpful than keeping kids in the classroom all day.

"Moving, running and playing outdoors freely have great influence on children. These activities play a role in children's abilities to focus and control themselves throughout the day," Marie Conti says, a famous educator of early childhood education. The mind cannot be educated without using the body. Learning is a whole of thinking and moving," she added.

Recess time makes it possible for children to learn something they can't get in class. Asking other kids to play, explaining the rules of a complex game and ending arguments are all important life lessons that children can only learn if they're given time to play. When something unhappy happens, children can find a way to get back to having fun themselves.

The physical activities kids take part in during recess can also reduce stress levels and allow children to feel more relaxed. In an education system that. Continues to place higher expectations on children to perform to a certain standard, less stress is just what the doctor ordered.