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.

    Do you sometimes argue about what seems to you to be a simple fact? Do you argue whether it's cold outdoors or whether the car in front of you is going faster than the speed limit (限速)?

    If you get into such arguments, try to think about the story about the six blind men and the elephant. The first blind man who felt the elephant's trunk (象鼻) said it was like a snake. The second who felt the elephant's side said it was like a wall, while the third said it was like a spear( 矛 ) as he touched the animal's tusk. The fourth, who took hold of the elephant's tail insisted that it was like a rope. The fifth man said it looked liked a tree as he put his arms around one of the elephant's legs. The last, who was tall and got hold of the elephant's ears, said it was like a huge fan.

    Each man's idea of the animal came from his own experience. So if someone disagrees with you about a “simple fact”, it's often because his experience in the matter is different from yours.

    To see how hard it is for even one person to make up his mind about a “simple fact”, try this simple experiment. Get three large bowls. Put ice water in one. Put hot water in the second. Put lukewarm water (温水)in the third. Now put your left hand in the hot water. Put your right hand in the lukewarm water. Your right hand will tell you the water is cold. Your left hand will tell you it is hot.

    Sure, it's good to get along with your teacher because it makes the time you spend in the classroom more pleasant. And yes, it's good to get along with your teacher because, in general, it's smart to learn how to relate to the different types of people you'll meet throughout your life. But really, there's one super-important reason why you should get along with your teacher. Kids who get along with their teachers not only learn more, but they're more comfortable asking question and getting extra help. This makes it easier to understand new materials and do yours best on tests.

    When you have this kind of relationship with a teacher, he or she can be someone to turn to with problems, such as problems with learning or school issues.

    As a kid in elementary or middle school, you're at a wonderful stage in your life. You're like a sponge (海绵), able to suck up lots of new and exciting information. On top of that, you're able to think about all this information in new ways. Your teacher knows that, and in most cases, is thrilled to be the person who's giving you all that material and helping you put it together. Remember, teachers are people, too, and they feel great if you're open to what they're teaching you. That's why they wanted to be teachers in the first place to teach!

    Some kids may be able to learn in any setting, whether they like the teacher or not. But most kids are sensitive to the way they get along with the teacher, and if things aren't going well, they won't learn as well and won't enjoy being in class.

    Hundreds of years ago, news was carried from place to place by people on foot or by horse. It took days, weeks and sometimes months for people to receive news. Now it is possible to send words and pictures around the world in seconds. Billions of people learn about news stories of their own country and all over the world every day, either by watching TV or reading newspapers.

    Newspapers have been an important part of everyday life since the 18th century. Many countries have hundreds of different newspapers. How do newspaper editors decide which news stories to print? Why do they print some stories and not others? What makes a good newspaper story?

    Firstly, it is important to report new stories. TV stations can report news much faster than newspapers. Yet, newspapers give more about the same story. They may also look at the story in another way, or they may print completely different stories to those on TV.

    Secondly, a news story has to be interesting and unusual. People don't want to read stories about everyday life. As a result, many stories are about some kind of danger and seem to be "bad" news. For example, newspapers never print stories about planes landing safely; instead they print stories about plane accidents.

    Another factor is also very important in many news stories. Many people are interested in news in foreign countries, but more prefer to read stories about people, places and events in their own country. So the stories on the front page in Chinese newspapers are usually very different from the ones in British, French and American newspapers.

    One time a young man, who hoped to study law, wrote to Lincoln for advice, and Lincoln replied, "If you are determined to make a lawyer of yourself, the thing is more than half done already. Always bear in mind that your own determination to succeed is more important than any other one thing."

    Lincoln knew. He had gone through it all. He had never, in his entire life, had more than a total of one year's schooling. And books？Lincoln once said he had walked to borrow every book with in fifty miles of his home. A fire was usually kept going all night in the small house and he read by the light of it.

    He walked twenty or thirty miles to hear a speaker and, returning home, he practiced his talks everywhere﹣in the fields, in the woods, before the crowds. He joined several societies and practiced speaking on the topics of the day.

    A lack of confidence always troubled him. In the presence of women he was shy and dumb. Even when he was in love with Mary Todd, he used to sit there, nervous and silent, unable to find words, listening while she did the talking. Yet that was the man who, by practice and home study, made himself into the speaker who debated with the famous speaker Douglas! That was the man who, in Gettysburg address, rose to the heights of eloquence （雄辩） that have seldom been achieved in all the human history.

    Small wonder that, speaking of his own great barriers and painful struggle, he wrote, "If you are determined to make a lawyer of yourself, the thing is more than half done already."

    A shark moving around the coastline is normally a worrying sight，but this waterborne drone (无人机) threatens floating rubbish instead of people.

    Developed by Dutch company RanMarine, the WasteShark takes nature as its inspiration with its whale shark-like mouth. Responsible for collecting waste, the drone will begin operations in Dubai Marina in November after a year of trials with local partner Ecocoast.

    According to RanMarine, the WasteShark is available in both autonomous and remote-controlled models. Measuring just over five feet by three-and-a-half feet (1.5 meters by 1.1 meter), it can carry up to 352 pounds of rubbish (159.6 kg) and has an operational battery life of 16 hours.

    By 2016 there were approximately 150 million tons of plastic in the world's oceans. One paper from December 2014 estimated that over a quarter of a million tons of ocean plastic pollution was afloat.

    "WasteShark also has the abilities to gather air and water quality data, remove chemicals out of the water such as oil, and heavy metals, and scan the seabed to read its depth and outlines," said Oliver Cunningham, one of the co-founders of RanMarine. "Fitted with a collision-avoidance system, the drone uses laser imaging detection and ranging technology to detect an object in its path and stop or back up if the object approaches."

    "Our drones are designed to move through a water system, whether it's around the perimeter (周边) or through the city itself. The drones are that last line of defense between the city and the open ocean," added Cunningham. "WasteSharks are operating in Dubai, South Africa and the Netherlands and cost $ 17, 000 for the remote-controlled model and just under $ 23, 000 for the autonomous model."

    Dubai-based operator Ecocoast has two WasteShark drones. Co-founder Dana Liparts says they will clean waterfronts for clients including hotels and environmental authorities and that Ecocoast' intention is to have the collected rubbish recycled or upcycled. However, Liparts argues that cleaning waterways doesn't have a one-size-fits-all solution and requires a combination of new technology, preventative measures and changing people's attitudes towards littering.