Our sun is a star, and nine worlds (天体) move round it. Worlds like these are planets. But here are other stars, other suns, not only thousands of them, but millions of them. Do different stars have planets? We can see the planets round our own sun. But we haven't been anymore. The stars are too far away from us. Stars give out light, but the planets don't have any light of their own. So we can't see them. They are too far, and too dark. Still, we can tell that some stars have planets. While a big planet goes round, it pulls its star to one side. And sometimes we can see this. Then we know that the star has a planet. For example, Barnard's Star is a small red star. And it is the quickest star in the universe. But sometimes it moves slower, and then quicker again. We have known Bernard''s Star for many years, and now we are sure it has a planet.

    Birdwatching is becoming more and more popular in many parts of the world．

    Birdwatchers enjoy looking for and listening to different kinds of birds．To watch birds, all you need is a pair of binoculars, a field guide and love for birds．

    If you are just starting birdwatching, buy one of the cheaper pairs of binoculars．You can choose better ones when your needs and skills grow．A field guide helps you leam about the birds' appearances, calls and habits before birdwatching．

    When you are ready, it's best to go to the wild with someone who is more experienced．You can join a birdwatching group to learn about some beginning skills．A local bird club is ideal．

    Start birdwatching in the morning, when birds are searching for food．Most of the time, you will hear bird calls from all around you, but will not see any birds easily．Look for movement in trees, and bring your binoculars to your eyes．

    The most important work for a birdwatcher is to identify the birds he/she sees．A bird's shape, size, colour and habits can help a birdwatcher identify it．When you identify a bird, don't forget to take notes about it on your notebook．

    To find more and different birds, you may wish to plan trips to birds' different living areas： forests, lakes, rivers, wetlands, etc．

    When watching the birds, you should always keep in mind： respect wildlife and protect its living areas．

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.

    Now too much CO makes the Earth warmer and warmer, and brings bad effect to people. To save our Earth, a new lifestyle called low-carbon life becomes popular. Low carbon means low energy and no waste. It is necessary for everybody to learn to live a low-carbon life.

    To live a low-carbon life, we'd better save as much energy as we can. For example, turn off the lights and TV when you don't use them, use cold water to wash clothes or dishes: take a short shower and try to take a cold one when the weather gets warm: don't do the cooking with electricity.

    To live a low-carbon life, we should eat less meat. Being a vegetarian can help reduce (v)one and a half ton of carbon dioxide a year, but keeping animals for food produces even more carbon dioxide than all the cars do in the world.

    To live a low-carbon life, we should plant more trees. Trees are very important for us. They can not only produce oxygen for us to breathe and keep the air clean. But also take in the harmful gases from the air. To protect trees we should stop people from cuing down trees and plant as many trees as we can.

    If we can keep them a habit in our daily life, the earth will become a safer planet for us to live on.

Every morning，many people in China do tai chi. It is popular with women and men. Tai chi is a kind of good exercise for old people. (A)它对身心都有好处。It is healthy and relaxing. Tai chi is from China. It is hundreds of years old. Tai chi is a "soft" martial art (武术). It is slow and calm (平静的). 

There are also "hard" martial arts. Shaolin kung fu，for example，which has a history of over 1，500 years，is a "hard" martial art. It is fast and dangerous (危险的). You have to be very healthy and strong to do "hard" martial arts. 

In Beijing，Master Li is teaching Shaolin kung fu to thirty young students. Three of the students come from abroad (国外). "Shaolin kung fu is difficult，" said Master Li. "(B)You have to practice every move many times. "

Sports like football and basketball are also popular in China. But martial arts like tai chi and kung fu are part of Chinese culture (文化) and history. 

{#blank#}1{#/blank#}: their family names, given names and courtesy names (字)

Take the famous poet Li Bai as an example. His family name was Li, his given name was Bai. {#blank#}2{#/blank#}

People used their given names when they were among family members. But in social life, they called each other by their courtesy names to show respect. {#blank#}3{#/blank#} If you were talking about yourself, or if your elders were talking about you, the given name would be used instead of the courtesy name. 

Men would get their courtesy names when they turned 20. It was a symbol of adulthood(成人). {#blank#}4{#/blank#}

{#blank#}5{#/blank#} For example, Mencius' name was Meng Ke (孟). His courtesy name was Ziyu (子舆). Both Ke and Ziyu mean "carriage(马车)". Zhuge Liang's given name was Liang, which means "bright". His courtesy name was Kongming, which means "very bright".