One weekend in May 2015, over 48 centimeters of rain fell in Houston, Texas, USA. Soon the city was covered with water. The rising water rushed into the cars on the roads. There were 16 deaths that weekend.

      Changing Weather

      The weather is changing. Over the last few years, heavy rains have caused floods (洪灾) in Brazil, Pakistan, and Thailand. Droughts (干旱) have struck Russia and Australia. Heat waves have killed thousands in Europe. There are more different kinds of terrible wild weather all over the world. In 2011 alone, the bad weather caused the world to lose 150 billion dollars.　

      Warmer and Wetter

      As more wild weather events happen, a worried world is beginning to ask questions like: What is going on with the weather? And why? Many also want to know: Is this natural, or are we to blame (责怪)?

      The answer seems to be: a little of both. Wild weather is natural.   ▲   This global (全球的) warming makes heat waves more likely to happen. The higher temperatures also cause more water to enter the air. This causes much more rain. Some scientists also believe global warming makes some storms stronger.

      This means we're likely to see more wild weather. “But we don't have to just stand there and take it,” says Scientist Michael Oppenheimer. He and other scientists say we need to stop the Earth from getting warmer. We also need to be prepared, to do things that will help save lives.

D

    You don't need to get in a time-travelling machine to see how technology will change our lives, such as the way we shop. Several new technologies that are to change your buying habits already appear. Let's see what's in store for your future shopping.

    Try it on, virtually（虚拟地）. Want to shop online for a new pair of glasses? You don't need to guess which pair looks best on you—use the eBay Fashion iPhone app to try a pair of glasses you're checking out on a picture of your face. But what about buying something bigger? Thanks to Microsoft Kinect's action tracking（跟踪）camera, you can cover clothes on your screen body. You can even choose the background of your virtual fitting room to improve your shopping experience.

    Get a perfect, custom fit. Everyone's body is shaped differently. To get a perfect fit, you sometimes have to get your clothes changed. But by using 3D scanning technology, all the clothes you buy will fit your body perfectly. Some companies scan（扫描）your body using High-tech to get the real sizes, so they can make special clothes just for you.

    High-tech shopping carts（推车）and checkout counters（收银台）. High-tech shopping carts could be common in malls and supermarkets in the future. Microsoft Kinect-enabled carts are under test. The cart can follow you along the aisles（通道）, controlled only by your movement and your voice.

    In the United States, several supermarkets use a certain set called “Scan It” that gives buyers the freedom to scan products on their own while they shop. If we don't want to wait in line before the checkout counters, we can use Toshiba's new object Recognition Scanner. The machine identifies（辨认）a product as soon as it's placed in front of a camera just by its shape and color, even if it has no bar code.

    There's much to see under the sea, but you need to remember that light behave differently in water than in air. The objects appear closer to you than they exactly are. You might find yourself reaching out to touch something and completely missing it.

    Objects under water will appear larger than they would on the surface, too. Be careful not to tell any stories about the big fish that got away. That fish might not be so big after all! It's just because sometimes things can seem to be as much as about 33 percent bigger in water!

    What's more, in deeper water, colors just don't seem as bright. In fact, it looks as if some colors are missing. Remember the color of an object results from the wavelength (波长) of light that are reflected (反射) from its surface. And light is taken in as it moves down through the water.

    Swimmers wear wet suits to keep warm underwater. Let's take a bright red, yellow, and blue wet suit as an example. These colors are hard to miss on the surface of water. Watch carefully the changes in color as you descend in the water. The red part now looks almost black because the red light wavelengths, the longest among these three colors, are missing. As you go down deeper, the same thing will happen to the yellow part and in the end to the blue part. Even at a place of about 6 to 9 meters underwater, you will look terrible, like a ghost(鬼怪) ! And you have to wait for your return to the surface to enjoy the bright colors again!

    Do animals have a culture? What do we mean by "culture?" Lately social scientists have begun to ask if culture is found just in humans, or if some animals have a culture too. When we speak of culture, we mean a way of life a group of people have in common. Culture includes the beliefs and attitudes we learn. It is the patterns of behavior that help people to live together. It is also the patterns of behavior that make one group of people different from another group.

    Our culture lets us make up for having lost out strength, claws, long teeth, and other defenses. Instead we use tools, cooperate with one another, and communicate with language. But these aspects of human behavior, or "culture," can also be found in the lives of certain animals. Animals can make tools, for example. We used to think that the ability to use tools was the dividing line between human beings and other animals. Lately, however, we have found that this is not the case. Chimpanzees(非洲小猩猩) can not only use tools but actually make tools themselves. Animals can also share knowledge with each other and use their own language to communicate. So it may be important for us to know that the line dividing us from animals is not as clear as we used to think.

    A black hole is a place in outer space with very strong gravity. Gravity is a great force(力量) that shapes the universe. On Earth, gravity makes apples fall from trees. It keeps your feet planted on the ground. The gravity in a black hole is much stronger. It is so strong that nothing around it can get away from it, not even light.

    Black holes are invisible. We can't actually see them because they don't throw back light. But scientists can find them with space telescopes(望远镜)and special tools. The strong gravity makes nearby stars move in a certain way. By studying how the stars move, scientists can find out if they are flying around a black hole. Strange things happen around black holes. This makes black holes a popular subject of science fiction(科幻)stories, although they are very real.

    A black hole forms when a star dies. The star falls in on itself and turns into a very small point. Because of its small size and huge mass(质量), the gravity will be so strong that it will pull light in and become a black hole. Black holes can grow huge as they continue to pull other things in and "eat" them. Many scientists believe that there are super-massive black holes at the center of galaxies, including the Milky Way.

    The idea of the black hole was first suggested by two different scientists in the 18th century: John Michelle and Pierre-Simon Laplace. In 1967, a physicist named John Archibald Wheeler came up with the name “black hole". Studying black holes can tell us many things about our galaxy and help scientists answer questions about the universe.