A smart home is a home with a communication network. This network connects devices(装置), such as lights and TV sets, and allows them to be controlled from far away through electrical wiring, mobile phone communication or WiFi over the internet.

    More and more people may start to consider owning a smart home, because it makes life much more convenient. It can help keep your room at a certain temperature. It can record what happens inside the home and send the video to your phone. When you are on vacation abroad, you can use a smart home controller to switch on or off the electricity when necessary. Some smart homes can receive a visitor, allowing him to come in and offering him a drink. They can even feed the cat and water the plants.

    Besides, smart homes are easy to fix. Most smart home technology and devices are wireless and can be set up with a minimum of tools,using only the guiding information. When a problem appears,you can deal with it yourself without paying a professional.

    However, for home-users,the smart home technology is far from perfect.It can be rather expensive to own the technology and the devices. Also, because the smart home system(系统) allow its owner to get home information from anywhere, it leaves the home easy to be attacked by hackers(黑客), who may secretly use or change the information in the system.

Now,many scientists are excited at the future of smart home technology. Imagine being able to get fashion advice from your mirror, or receive food shopping suggestions from your refrigerator. While there are others who worry that those smart devices will make people lazier and lonelier. Whatever it is, one thing is for sure—smart home technology will change the way we live and work.

Have you ever experienced the feeling of falling as you start to fall asleep? Sometimes you may come to realize this feeling. If so, don't worry. Many people have felt the same thing.

In fact, these muscle twitches (肌肉抽搐) in the arms, legs or other parts of the body are called hypnic jerks (入睡抽动) or sleep starts. And they are very common. Up to 70 percent of people experience them sometimes, Huffington Post reported. But what causes it?

There are some theories(理论). Some scientists believe that the feeling of falling comes from the body relaxing itself, especially if the person is anxious or unable to get comfortable. As you're about to sleep, your muscles become relaxed. But your brain stays awake. It misunderstands the relaxing of your muscles as a sign that you're falling. Then the brain jerks the body awake as if it's trying to protect you.

    Other scientists believe that different phases of sleep might cause the hypnic jerks. When we sleep, we experience two phases: non-rapid eye movement (NREM) and rapid eye movement (REM). During REM, our heart rate (心率), breathing and nervous system can act irregularly (不规律地). If the body experiences flashes (一瞬间) of REM while entering sleep, these irregularities could cause twitches.

If you don't want to experience hypnic jerks, scientists have some suggestions. When you become deeply relaxed, you can learn how to reconnect slowly by moving your fingers and toes a little bit. Then start to move your head and open your eyes, while being aware of yourself as you get out of the relaxed state.

    But experts agree that hypnic jerks, though sometimes scary, are harmless. If it wakes you up, simply roll over and go back to sleep. But keep in mind: a caffeinated (含咖啡因的) drink, exciting evening activities or stress may make hypnic jerks happen more often.

     We often read the Air Quality Index （空气质量指标） or AQI reported in the newspaper. The AQI helps us understand what the air quality around us means to our health. The AQI uses colors, numbers and words to tell us about the air. Let's see what these colors and numbers mean.

    In recent history, there have been some amazing inventions which have changed our lives. The plane has made international travel faster and easier. The Internet has brought people closer. And you must know the names of some famous inventors like Henry Ford or Steve Jobs. But there are many everyday objects which you probably don't notice and you don't know who invented them. Take for example Nils Bohlin who invented the modem-day car seat belt (安全带).

    Before 1959, only two-point seat belts were available, and the only people who often wore them were race car drivers. The two-point seat belt couldn't protect passengers from internal injuries (内伤) during serious car accidents.

    In 1958, Bohlin joined Volvo Car Corporation as a safety engineer. Then he came up with the three-point seat belt to keep passengers from flying out of their cars during collisions. The three-point seat belt used one strap (带子) across the chest (胸部) and another across the legs and then the two joined at me same place.

    Amazingly, this was a very simple idea which no one had tried before. The three-point seat belt was introduced on Volvo cars in 1959. For more people's safety, Volvo made the new seat belt design available to other car makers for free. Since then, engineers have worked to improve the three-point seat belt, but the basic design remains Bohlin's.

    At the time of Bohlin's death in September 2002, Volvo announced that the seat belt had saved more than one million lives since it was introduced.

    Babies born after 2017 may never need to take a driving lesson because of the development of self ­driving cars. Some scientists say that self ­driving or driverless cars(无人驾驶汽车)may hit the roads within 15 years, and it is possible that driving may become unnecessary, or more relaxing and enjoyable.

    Companies like Google, Baidu, Apple and Alibaba are working on driverless cars. But, if the tests are successful, these electric self­ driving cars could be put into use very soon. This kind of cars may change the way we live in the future. All you have to do is to type in the address!

    According to Baidu, driverless technology has the following four advantages. Firstly, driverless cars are actually safer. With driverless cars, the number of deaths caused by accidents will decrease. Secondly, driverless cars are more efficient(效率高的) than manned cars. Thirdly, driverless cars follow the traffic rules. Therefore traffic control will be easier to achieve. At last, the cost of transportation will be reduced as the labor cost becomes less.

    There are many different technologies needed to make a successful self ­driving car. The most difficult technologies of all are environmental perception(感知), behavior prediction, planning control, HD mapping, and exact GPS.

    "Without music, life would be a mistake, "famous German philosopher(哲学家)Friedrich Nietzsche said over a century ago. Music is a big part of our lives. But in recent years, some American schools have cut music classes to control budgets(预算).

    For example, Chicago public schools hurt arts education when it fired over 1, 000 teachers. Among them, 10 percent of the teachers taught art or music, according to The Washington Times. In fact, this is not just a problem in the US. In other countries, such as China and the UK, music classes are not thought to be as important as ones like science, math and history. That's partly because music is not seen as a very important life skill, and it isn't tested. Many students are busy with schoolwork, so parents and students choose to focus on subjects that are tested more often.

    However, learning music is beneficial(有益的)in many ways.

    When playing music, you need different abilities to work together. It is not as simple as it looks, according to Kenneth K. Guilmartin of Music Together, an early childhood music development program. For example, when playing the piano, people see music notes and decode(解码)them in their brains. They also use their fingers to make sounds. You need to deal with all these things at the same time.

    Music has a special connection with science as well. You can see that many scientists are good at playing music：Einstein played the violin and German physicist Max Planck was talented in playing the piano.