Radios, telephones and televisions are widely used in the world. When you switch on the radio, you can listen. But when you use the telephone, not only can you listen to others, but also you can chat with them. However, you cannot see anything at all. Television is much better than both of them. People can watch TV and listen to it, but they cannot take part in what they see.

    Today, some people are using a new type of telephone called vision phone. With it two people who are talking can see each other. Vision phones can be of great use when you have something to show the person whom you are calling. It may also have other uses in the future. Some day you may be able to call up a library and ask to read a book right over your vision phone. You may be able to do the shopping through it too. Perhaps in the near future, vision phones will come into our everyday life.

    Many objects in the universe are invisible, but they send radio waves. The radio telescope* thus appeared, and it is considered one of the greatest inventions in the twentieth century. Reber built the world's first radio telescope in 1937. Ryle and Hewish developed radio telescope systems for the location of weak radio sources, and they shared the Nobel Prize for Physics in 1974.

    A radio telescope is usually made up of:

    One or more antennas to collect the radio waves. Most antennas are made in the shape of a dish to collect and reflect, the radio waves to the sub—reflector, in the same way as a curved mirror focuses visible light to one point.

    A receiver and amplifier to receive the radio waves from the sub—reflector, and make these weak radio waves strong enough to be recorded and turned into electronic signals. To make an amplifier sensitive enough, it is usually cooled to, very low temperatures (e. g. as low as —270℃）.

    A recorder to keep a record of the electronic signals. Most radio telescopes today keep the signals to the computer's memory disk for astronomers to analyze later.

    Radio wavelengths are much longer than those of visible light, and the radio waves from deep space are always weak. To catch Radio wavelengths are much longer than those of visible light, and the radio waves from deep space are always weak. To catch these waves, radio telescopes usually have huge antennas. The sizes of most antennas in use today are around 50 to 300 metres in diameter. The antenna of FAST in Guizhou, China, the latest and largest radio telescope in the world, is 500 metres in diameter, as large as the size of 30 football fields.

    To avoid interferences, and keep the telescopes sensitive, radio telescopes are built in places where there are no human radio waves or electronic signals. For example, FAST is 5 kilometres away from the closest village and 25 kilometres away from the nearest town.

    Radio telescopes create pictures of the sky, not in visible light, but in radio waves. This is extremely useful, because there are objects that can't be seen, objects that we wouldn't even know without radio telescopes.

    Some Fun and Interesting Facts

    Do you think what color oranges are? The common answer to this question is "Orange". However, the first oranges from Southeast Asia were actually green. Up to now, oranges in warmer areas like Vietnam and Thailand still stay green when they are fully grown.

    There was a man named John Chapman who planted thousands of apple trees. But the apples on those trees were much more bitter(哭的) than the ones you'd find in the supermarket today. John didn't expect has apples to be eaten whole, but rather made hard apple cider(苹果酒).

    Like most four-legged animals, cats have five toes on the front paws, but their back paws only have four toes. Scientists think they four-toe back paws might help them run faster. Do you know any other fun fact about cats?

    Walt Disney might have been the firs it gloves on his characters，as the star Mickey Mouse in 1929's The Opry House（《奥普里之屋》）.Besides being easier to interest, there's another reason why Disney did so "We didn't want him to have mouse hands because he was supposed to be more human." Disney once said.

    Try to imagine a life without a memory. It would be impossible. You couldn't use a language, because you wouldn't remember the words. You couldn't understand a film, because you need to hold the first part of the story in your mind in order to understand the later parts. You wouldn't be able to recognize anyone - even members of your own family. You would live in a present forever. You would have no past and you wouldn't be able to imagine a future.

    Human beings have amazing memories. Besides all our memories about our own lives, we can recall (回忆) between 20,000 and 100,000 words in our own language as well as possibly thousands more in a foreign language. We have all kinds of information about different subjects such as history, science, and geography, and we have many skills such as driving a car or playing a musical instrument. All these things depend on our memory.

    How well you remember things depends on many different factors. Firstly, some people have better memories than others, in just the same way as some people are taller than others. Secondly, research shows that, you can store different things in different parts of the brain. Ideas, words, and numbers are stored in the left—hand side, while the right-hand side remembers pictures, sounds, and smells. In most people, one side of the brain is more developed than the other, and this may explain why some people can remember people's faces easily, but can't remember their names.

    Cars make our lives more convenient. But they can also be a problem. For example, fossil fuel(化石燃料) cars mainly cause air pollution.

    To improve the environment, many countries are developing electric vehicles(EVs，电动车). Among them, China is taking a leading role and has created the world's largest EV market.

    Last year, over 40 percent of the 753，000 EVs sold in the world were sold in China, more than twice as large as the number sold in the United States.

    "Filling up a fossil fuel car with gas(汽油) is more expensive than charging(充电) an electric car, " said Wu Hao, who bought an electric car this year.

    However, there are still some problems. It can be hard to find charging piles(充电桩) and the cars can't go far before needing to be recharged.

    Some of these problems are being solved. In 2014, China had 31，000 charging piles. Now China has the world's largest EV charging network, with more than 167，000 charging piles in total.

    Developing EVs is one of many efforts that China has made to cut down pressure on its environment after the government promised to stop increases in carbon dioxide emissions(二氧化碳排放量) by 2030.

    "As China goes, so will the world's car industry，" the Wall Street Journal said. China has taken a leading role in the world's electric vehicle industry.