Radio, telephone and TV are widely used in the world. When you turn on the radio, you can listen. But when you use telephone, not only can you listen to others but also you can chat with them, however, you can't see anything at all. TV is much better than both of them. People can watch TV and listen to it, but they can't take part in what they see.

    Today, some people are using a type of telephone called vision-phone（可视电话）. With it, two people who are talking can see each other. It is better than radio, telephone or TV.

    Vision-phones can be of great use when you have something to show the person whom you are calling. It will be helpful in people's life. Some day you may be able to call up a library and ask to read a book on your vision-phone. You may be able to do some shopping too. Perhaps in the future, people will use vision-phone.

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    If you go into the forest with your friends, stay with them. If you don't, you may get lost. If you get lost, this is what you should do. Sit down and stay where you are. Don't try to find your friends—let them find you. You can help them find you by staying in one place. There is another way to help your friends or other people to find you. You can shout or whistle (吹口哨) three times. Stop. Then shout or whistle three times again. Any signal (信号) given three times is a call for help.

    Keep up shouting or whistling. Always three times together. When people hear you, they will know that you are not just making a noise for fun. They will let you know that they have heard your signal. They will give you two shouts or two whistles. When a signal is given twice. it is an answer to a call for help.

    If you don't think that you will get help before night comes, try to make a little house with branches (树枝). Make yourself a bed with leaves and grass.

    When you need some water, you have to leave your little house to look for it. Don't just   walk away. Pick off small branches and drop (扔下) them when you walk to go back again easily. When you are lost, the most important thing to do is to stay in one place.

    The giraffe is the tallest modern land animal. It can be over 5. 5 meters tall. Its neck alone may be 1. 9 meters long. Yet the giraffe has only seven bones in its neck, the same number as in the humans'. Even a small bird has many more bones in its neck than a tall giraffe. Each bone in a giraffe's neck is very long, while the bones in a human's neck are short. That makes the difference. A female giraffe gives birth to one baby at a time. The baby, called a calf, is about 1. 9 meters tall at birth. By the age of eight it is full-grown. The giraffe eats mostly leaves. Because it has a long neck, it can reach the high leaves on the trees.

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    As our closest neighbor in space, the moon has been the subject of popular legends, songs and poems since ancient times. And it also attracts scientists deeply.

    But even after centuries of research, many questions remain to be answered about the Earth's only satellite.

    Perhaps the Chang'e-4 lunar probe will be able to find out more of its secrets. On Dec 8, 2018 the probe lifted off from Xichang Satellite Launch Center in Sichuan province. It is the first probe to the far side of moon in human history.

    The Earth's gravity slows the moon's rotation, matching it to the speed of its orbit. Thus, the far side of the moon is always dark and has never been seen.

    It's this sense of the unknown that makes the far side of the moon such an interesting place for scientific and space exploration. Long exposed to solar winds, the far side may have the special soil and minerals in its upper mantle.

    For this reason, Chang'e-4 will study the effect of solar winds on the lunar surface and any minerals found beneath the probe. Chang'e-4 is also carrying flower seeds and potato and silkworm eggs to see whether life is possible on the moon. If it is, then the moon will become a more likely destination for space travel in the future.

    However, because of communication problems, exploring the dark side will not be easy. As the far side is blocked off from us, radio noise coming off Earth is also blocked. This is why China launched the relay satellite Queqiao in May, 2018, so that communication between Earth and the probe could go ahead.

    Power supply is also a challenge to the mission. Chang'e-4 gets energy from the sun through its solar panels. However, a lunar day has the length of 28 Earth days. It means that the probe will need to orbit the moon for over 20 days to be in a position to be able to land in moon daylight and so use its solar panels.

    According to Xinhua, theChang'e-4 lunarprobe landed on the far side of the moon on Jan 3, 2019 successfully, and everything goes well.

    The New York Times described the journey as "groundbreaking", and wrote that it would "give clues to the history and development of the moon".

    In 1845, a deadly disease struck the farms of Ireland, killing all the Lumper potato plants. In another place or time, the death of single crop species (物种) might not have been so important. But in Ireland, in 1845, people depended almost solely on the potato for food. The death of one species caused a terrible famine(饥荒). Now, some scientists are worried that such a famine could happen again, but on a much wider scale.

    Over the centuries, farmers have discovered thousands of different species of food crops. Each species has special qualities. Some can be grown in very hot or cold climates. Others are not affected by certain diseases. However, you won't find many of these species in your local supermarket. To feed the seven billion people on Earth, most farmers today are growing only species of plants and farming only species of animals that are easy to produce in large numbers.

    For example, in the Philippines, there were once thousands of varieties of rice: now fewer than 100 are grown there. In China, 90 percent of the wheat varieties grown just a century ago have disappeared. Scientists believe that over the past century, we have allowed more than half of the world's food varieties to disappear.

    One solution to this problem is to collect and store the seeds (种子) as many different plant varieties as we can before they disappear. The idea was first suggested by Russian scientist Nikolay Vavilov. In the 1920s and 1930s, he collected around 400,000 seeds from five contients. More recently, others are continuing the work he began.

    In the U.S. state of Iowa, Diane Ott Whealy wanted to protect historic plant varieties, like the seeds her great –grandfather brought to the U.S. from Germany more than a hundred years ago. She and her husband started a place called Heritage Farm, where people can store and trade seeds.

    More importantly, the people at Heritage Farm don't just store the seeds; they plant them. By doing this, they are reintroducing foods into the marketplace that haven't been grown for years. These food species are not just special in terms of appearance or taste. They also offer farmers food solutions for the future, from the past.

    A British company has made a new product to help us save money. The product is a wristband that gives us an electric shock if we spend too much money. The wristband is called Pavlok. It is linked to our bank account. It knows how much money we have in the bank. If we go shopping and there is not enough money in our bank account, the wristband makes an electric shock on our wrists. This warns us not to overspend. The company is called Intelligent Environments. It wants to work with banks to help customers with their money. So far, no banks in Britain have said they would ask their customers to wear Pavlok. They could start doing this in the future.

    The Pavlok wristband is part of the Internet of Things. This is the idea that everything in our life will be connected to the Internet. The CEO of Intelligent Environments, David Webber, said people liked the idea of the Pavlok. Shoppers would rather get a small electric shock in the store from the wristband than get a big shock later when they see their bank account. Mr. Webber said the Pavlok would be great for people who cannot stop spending because they have no power or their power is weak. He added that many young people have the "ostrich effect". This is when people put their heads in the sand and buy things rather than look at how much money they have in their bank accounts.