The African elephant, which is the largest land animal remaining on earth, is of great importance to African ecosystem. 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.

    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 under-bushes, 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.

    In most languages, a greeting is usually followed by "small talk". Small talk means the little things we talk about at the start of a conversation. In English-speaking countries people often make small talk about the weather: "Nice day isn't it?" "Terrible weather, isn't it?" But there is something special about small talk. It must be about something that both people have the same opinion about. The purpose of small talk is to let both people agree on something. This makes meeting people easier and more comfortable. People usually agree about the weather, so it is a safe topic for small talk. But people often disagree about religion or politics so these are not suitable topics for small talk in English. The topics for small talk also depend on where the conversation is taking place. At football matches, people make small talk about the game they are watching, "Great game, isn't it?" At bus-stops, people may comment about the transport system, "The bus service is terrible, isn't it?"

    Greetings and small talk are an important part of conversation in any language. The way people greet each other and the things they talk about, however, may be different from one language to another. This shows that there is much more to learn when we learn a language than just the vocabulary and the grammar of the language. We also have to learn the social behavior of the people who speak it.

    Parents may think they're smart about where they store medicines, but their kids are smarter. Nearly 60,000 young children are rushed to the hospital every year after getting into medicines not meant for them, according to a new report from Safe Kids Worldwide.

    The report finds little connection between what parents know about storing medicines safely and what they actually do. Nine out of 10 parents know that medicines should be stored up and away out of reach and sight, but 7 out of 10 of them admit not doing that. They leave medicines out on kitchen counters, sinks and sofas, believing babies and toddlers(学步者)aren't tall enough or strong enough to reach them. Unfortunately, they probably can. Children as young as a month have ended up in an emergency department because they'd been poisoned by getting into a medicine that was left within reach.

Most poisonings related to medicines—particularly among babies and toddlers—occur within their home. Kids develop rapidly and they want to explore their environment. At certain ages they have a lot of hand-to-mouth activity, and so it's very common for them to explore their environment and then try to taste what they find.

    The new Safe Kids worldwide report includes a survey of 2,000 parents with children under age 6. While the number of children visiting an emergency department for accidental poisonings had declined since the 2010 maximum, the decline has slowed in recent years.

    Prescription and over-the-counter medicines cause the most severe poisonings, but vitamins and supplements(补充品)can also cause problems. There are steps families can take to lower the risk for an accidental medicine poisoning.

    A killer whale(虎鲸) that can copy words such as “hello” and “bye-bye” is thought to be the first of its kind to copy human speech.

    The female killer whale learned to “speak” some human words by copying a trainer at a park in France. The animal's ability includes speaking the name “Amy” and “one, two, three”.

    Whales and dolphins are among the few animals except humans that can learn to produce a sound just by hearing it. “It is not often seen,” said Dr Josep Call, a co-researcher on the study. “Humans are good at it…Interestingly, the animals that can do best are marine mammals(海洋哺乳动物).” The researchers start to find out whether killer whales could learn new words by copying others. They studied a female named Wikie at Marineland Aquarium in Antibes, France. She was taught to speak human words.

    Dr Jose Abramson, a co-researcher on the study, said basic “conversations” with Wikie may one day be possible. He said,” It has been done before with a famous grey parrot and dolphins using American sign language(手势语).” However, he said they have to be careful about introducing human ideas on animals, as there is more to learn by trying to understand the natural way each kind communicates in its own environment. Wikie made sounds in water, which may be quite different.

    Dr Alex Thornton, senior speaker at the University of Exeter, said they still don't fully understand why some animals learn to copy. Some animals copy sounds to attract possible partners, while others copy sounds to become a member of a group. “Some whales, for example, learn their calls from one another to mark them out as members of their social group,” said Dr Thornton, who doesn't join in the research.

    It's nearly exam time, so check out some of the best free apps around to help you manage the stress of exams and ensure you are studying effectively over the coming weeks.

    Exam Countdown

    This app can help to remind you how many days, hours, and minutes you have until your exam. This can help to motivate you to hit the books before it's too late.

    Block The Internet

    Are you constantly checking Facebook when you should be writing an essay? Or perhaps are you distracted by a battle in League of Legends? Download this app to get rid of online distractions by temporarily blocking Internet sites on your mobile. Simply add the websites you want to block and the period of time to block them for. Guarantee to get yourself focused on that assignment.

    CBT-i Coach

    The US Department of Veterans (老兵) Affairs developed the app, CBT-i Coach, to assist with insomnia (失眠) and help people who would like to improve their sleeping habits. It provides several key parts: information about sleep and insomnia, strategies for improving sleep, relaxation skills and a helpful sleep diary.

    Yoga

    Yoga has great health benefits both for the mind and body, and will help you to perform at your best while at university. Download a yoga app and have your own personal yoga instructor in your living room. You can choose from short or long workouts and have a qualified instructor teaching you how to do each pose. Choose from a variety of yoga routines and watch the instructional videos. Go on, stretch out those sore muscles.

    There are two kinds of secrets: secrets of nature and secrets about people. Natural secrets exist all around us; to find them, one must study some undiscovered aspect of the physical world. Secrets about people are different: they are things that people don't know about themselves or things they hide because they don't want others to know. So when thinking about what kind of company to build, there are two distinct questions to ask: What secrets is nature not telling you? What secrets are people not telling you?

    It's easy to assume that natural secrets are the most important: the people who look for them can sound authoritative (权威的).This is why physics PhDs are difficult to work with—because they know the most basic truths, they think they know all truths. But does understanding electronic theory automatically make you a great marriage counselor? Does a gravity theorist know more about your business than you do? At PayPal, I once interviewed a physics PhD for an engineering job. Halfway through my first question, he shouted, "Stop! I already know what you're going to ask!" But he was wrong. It was the easiest no-hire decision I've ever made. Secrets about people are relatively overlooked. Maybe that's because you don^'t need a dozen years of higher education to ask the questions that uncover them: What are people not allowed to talk about? What is forbidden or taboo?

    The best place to look for secrets is where no one else is looking. Most people think only in terms of what they've been taught; schooling itself aims to spread basic wisdom. So you might ask: are there any fields that matter but haven't been standardized? Physics, for example, is a real major at all major universities, and it's set in its ways. The opposite of physics might be astrology, but astrology doesn't matter. What about something like nutrition? Nutrition matters for everybody, but you can't major in it at Harvard. Most top scientists go into other fields. Most of the big studies were done 30 or 40 years ago, and most are seriously flawed (有缺陷的). The food pyramid that told us to eat low fat and large amounts of grains was probably produced by Big Food(美国著名食品公司)than real science; its chief impact has been to worsen our obesity(肥胖)problem. There^'s plenty more to learn: we know more about the physics of far away stars than we know about human nutrition. It won't be easy, but it's not obviously impossible: exactly the kind of field that could produce secrets.