Have you seen Avatar《阿凡达》? It's a popular 3D movie, and you may have to wear 3D glasses to see it. The 3D glasses make the images(图像)from the movie look as if they were coming straight towards you. 

 More and more 3D movies are coming to theaters. Some say that 3D TV sets will come into our homes in the near future. 3D technology can make TV and movies are more exciting. However, people with eye problems may get headaches if they spend too much time watching 3D movies. Why?

When we look at an object(物体), each eye sees it at a different angle(角度). Our eyes send the two images to our brain(大脑), and the brain puts them together. 3D technology uses two film projectors(投影机). One projects a left-eye-image and the other projects a right-eye-image. 3D glasses allow us to see a different image in each eye. So, when we are watching a 3D movie, our brain can't put together the images sent to our eyes. The brain needs to work harder at “reading” the images. That makes it easier for people with eye problems to get dizzy(头晕的) or have headaches. A famous eye doctor said if your eyes can't focus(聚焦) on the same object at once, you will have trouble watching 3D movies.

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    Plants are very important. This is because plants can make food from air, water and sunlight. Animals and man cannot make food from air, water and sunlight. Animals can get their food by eating plants and other animals. Man gets his food by eating plants and animals, too. So animals and man need plants in order to live. This is why there are so many plants around us.

    There are two kinds of plants: flowering plants and non-flowering plants. Almost all the trees around us are flowering plants. You can know some trees from their flowers and fruit. Non-flowering plants do not grow flowers. You cannot see many non-flowering plants around you.

    If you look carefully at the plants around you, you will find that there are many kinds of plants. Some plants are large and some are small. Most of them are green. Thanks to the plants around us we can live on earth.

    Let's take a look at the cool inventions in science and technology.

Robot-teacher

    Some students in South Korea have new language instructors: the English-teaching robots. The robots help students practise speaking English. South Korea employs many foreigners to teach English. The robot-teachers can help to solve a shortage of English teachers. Can robots replace human teachers one day?

Superhero suit

    Have you ever dreamed of becoming a superhero? There's a real Iron Man suit, XOS 2. The suit provides the power to lift 200 pounds and break the wood easily. It was designed to help the military with heavy lifting. One person in the suit can do the work of three soldiers.

Hard-working robot

    The EMIEW2 robot is a perfect office helper. It can guide visitors to the places they want to go. The three-foot-tall robot can know different human voices and react to instructions. One day, it may work as a receptionist or a guard.

    Fresh green grass, Hundreds of colorful wild flowers. Water running into little pools. Birds making their homes in boxes. The 9, 500-square-metre Augustenborg Botanical Garden may look just like any other well-organized park but there's a difference. It lies on the roofs (屋顶) of industrial and office buildings in the city of Malmo in Sweden.

    Green roofs are not a new invention. And now they are getting popular again. The common roofs of a modern city have endless black surfaces with no life or water. Perhaps that's why a garden on a roof becomes such a perfect choice for more and more people.

    Green roofs are not just pretty. They also help to moderate the city temperature. The high temperatures on common roofs in the summer can make top floor flats uncomfortably hot. What is more, they play a part in making the cities hotter than the countryside around them, causing the "urban heat-island effect". On a green roof, however, with its plants and water, temperatures change only a little, as they do in a park. This can greatly cut the costs of heating and cooling in the building below.

    Also, a green roof takes in rain water, and protects the city drainage (排水) system.   ▲    And small animals and birds can make their homes on it. Thanks to this, the city may become part of nature, rather than something completely separate from it.

    While the cost of building such a roof can still be higher, it can be cheaper in the long term as a result of energy savings. And wouldn't it be wonderful to be able to walk out into a garden high above the city's noise and traffic, whether you're at school or in an office or just at home in a ten-floor block?

    China has a very long history. It has many great traditional skills that have a wide influence (影响). Here we mainly talk about kites.

    The earliest mention of a kite in ancient China dates back to the 5th century BC. It was made of wood and used as a rescue signal (求救信号).

    At the time between 770 and 221 BC, Chinese kites were actually called "muyuan". They were first invented in Shandong Province for military purposes (军事目的). The kites were used to send important messages during the Chu-Han War. During the Tang Dynasty, kites were made of lighter materials, such as bamboo, silk and paper. At that time, people began to fly kites for other purposes. It was believed that letting go of the kite could remove bad luck and illness.

    Today, kite-flying is an interesting and healthy activity in China. There are large kite-flying festivals held throughout the country, and kite makers can show off their skills during the festivals.

Nature is amazing! Take a close look at the world of insects, and you'll discover many unbelievable things. Consider butterflies (蝴蝶), for example. They have beautiful wings and magical flying skills. On summer days, you always see them flying freely over flower gardens and wild fields.

But did you know how butterflies become the flying insects? It is one of the wonders of nature. In the beginning, the mother lays a small and colourful egg on a leaf or stem of a plant. It is hard to believe that the egg will become something completely different in a few days. It becomes a walking insect. This insect is called a caterpillar. It now has legs, eyes and a large body. A new life begins. The caterpillar can eat, walk and see. But it is still not a butterfly.

Soon, after growing big, the caterpillar makes a cover for itself. It covers itself in the nice protective blanket (保护层) and goes to sleep. This is known as the "pupa (蛹)" stage. After some time, the blanket breaks and a wet butterfly appears. It now has six legs, a mouth, eyes and wings. Shortly, the beautiful butterfly spreads (张开) its wings and flies away. After a few weeks, this butterfly lays her eggs, and the cycle (循环) begins all over again.

This is just one example of the wonders of nature. Look around the natural world, and you will learn many truly amazing things.