As a result, songs sound like noise to an amusic. Many amuics compare the sound of music to pieces of metal hitting each other. Life can be hard for amusics. In fact, most people cannot understand what it feel like be amusic. Just going to a restaurant or a shopping center can be uncomfortable or even painful. That is why many amusics have to stay away from places where there is music. However, this can result in social loneliness. "I used to hate parties,"says Margaret, a seventy-year-old woman who only recently discovered that she was amusic. By studying people like Margaret, scientists are finally learning how to identify(辨别) this unusual condition.

  Scientists say that the brains of amusics are different for those of people who can enjoy music. The difference is complex(复杂的), and it is not connected with poor hearing. Amusics can understand other non-musical sounds well. They also have no problems understanding common speech. Scientists compare amusics to people who just can't see certain colors.

Many amusics are happy when their condition is finally diagnosed(诊断). For years, Margaret felt embarrassed about her problem music. Now she knows that she is not alone. That makes it easier for her to explain. "When people invite me to a concert, I just say "No, thanks. I'm amusic." says Margret.

B

    Many children spend a lot of time watching or playing with electronic media –from televisions to video games, computers and other devices（设备）.

    So, it is natural that parents should wonder about the time children spend looking at a TV or computer screen. Americans say “screen time” when they talk about any time children spend in front of an electronic device.

    Perhaps parents can stop worrying so much about screen time, at least for older boys and girls. In October 2016, the American Academy of Pediatrics (AAP) listed several suggestions for parents and child care workers. Here are some of the suggestions.

●Avoid digital media use in children younger than 18 to 24 months.

●For children aged 18-24 months, avoid letting the child watch media alone. And avoid using media as a way to comfort your child.

●For children two to five years of age, allow one-hour screen time on “high-quality（质量）programming” a day and watch it with your child.

●For children aged 6 and older, don't spend too much time using media. Also, make sure that screen time does not take the place of healthy sleep, exercising, doing homework and other activities.

●Make sure to have media-free time together as a family, such as dinner or driving. Also make some areas of the home media-free. Turn off you child's electronic devices an hour before bedtime.

    Most people agree that trees look nice, but not everyone knows that trees can also help cities save money. A few years ago, the US Forest Service studied trees in Chicago. They found that just one tree can save a city hundreds of dollars over its lifetime.

    Trees can save money by helping people save energy(能源). Trees stop the sun shining on buildings. They also block(挡住) the winter wind. That helps people use less energy to make their homes or offices warm or cool. Saving energy is saving money.

    Trees have another way to help a city save money. When it rains, there will be a lot of water in a city's sewers (下水道). Cities need lots of money to clean that water. But before the rainwater gets to the dirty sewers, trees can take some into themselves. With the help of trees, there is less water to clean.

E

    Artificial intelligence（人工智能）, or AI in short, is the science of giving computers and machines ability to think and work like humans. AI scientists and engineers have made a lot of cool technologies.

    AI is rapidly catching up with the human ability to read faces. As a result, facial recognition（识别）is used a lot in the world. Chinese police use this technology to identify criminals（罪犯）.Once they caught a criminal when he attended a concert. It also checks the ID of ride-hailing（网约车）drivers and lets people pay for things with a smile.

    AI is also used in self-driving cars, which are believed to be the future of driving. Most drivers may wave or nod at passers-by to let them cross the street, but self-driving cars don't have this ability. Carmakers are testing a light signal system to help them "speak" to humans. The system can show what self-driving cars will do. For example, if a driverless car is yielding（让路）, it will flash two white lights side to side. A rapidly flashing light tells passers-by that the car is about to speed up.

    Service Robots also show you know powerful AI is. Imagine this—you come back home from school and your robot housekeeper is waiting for you at the door. After dinner, he teaches you to play the piano, just like a real music teacher. Such thoughts will soon happen in the real world. In the future, more and more service robots will become good home helpers.

    AI is so powerful that it can help human beings and even replace us in many jobs.

    Have you ever stood beside the ocean and stared at the waves (波浪)? The way they move is changing! Nothing is more peaceful than watching the movement of water.

    Every ocean has waves. Unless you are lucky enough to live by the sea, though, you probably can't watch the waves very often. How would you like to have your own wave machine? Making one is easy and a lot of fun.

    Now that you have made your ocean, put your bottle on its side. Wait a minute. The water win be on the bottom. The oil and paint thinner mixture will be on the top. Now tip (倾斜) the bottle back and forth (反复来回) and watch the waves.