The best-known (最熟知的) vegetable in the world is the potato. It grows in many places and does not need rich soil(土壤) like many other crops. But until four hundred years ago, the Europeans(欧洲人) began to know the potato. But today it's one of the main foods in Europe(欧洲). About half of the world's potatoes are grown in Europe.

    In France the potato was not grown for a long time .Here is story about Louis. In 1778 he saw some potato flowers for the first time .He liked them so much that he picked one and put it in his buttonhole. He was interested in the flowers not the potatoes themselves.

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    The Earth is our home; we must take care of it. This means keeping the land, air and water clean. Pollution is a dirty word. To pollute means to make things unfit or unclean to use. Pollution comes in many ways. We see it, smell it, taste it and drink it. Pollution is beginning to threaten (威胁) our health, our happiness and our life. Man has been polluting the earth from the time he first made fire, washed his clothes in the river and threw his waste on the ground. When land was used up or water became dirty, men moved on to another place. At first, the problem was not so serious because there was plenty of clean air, land and water. There weren't so many people then and their wants were fewer. All the dirty things could be absorbed (吸收) by nature and soon covered over. But this is no longer true. The increase of population and the development of industry(工业)have changed that. Man is slowly poisoning (毒害) his environment. Through the use of poison, man has polluted the land, killing the animals. By putting dirty water and chemicals into rivers and lakes we have polluted our drinking water, killing the fish.

    Our increasing population is part of the problem. More people, more waste.

    Where is this all to end? Are we turning the world into a big rubbish dump (堆存处), or is there any hope that we can get rid of (摆脱, 除去) the pollution? Luckily, millions of people have been warned of the danger of pollution. Large numbers of people are now working hard to bring pollution under control.

    In 1901, H. G. Wells, an English writer, wrote a book describing a trip to the moon. When the explorers (探险者) landed on the moon, they discovered that the moon was full of underground cities. They expressed their surprise to the "moon people" they met. In mm, the "moon people" expressed their surprise. "Why are you travelling to outer space when you don't even use your inner space?" they asked.

    H. G. Wells could only imagine the travel to the moon. In 1969, human beings really did land on the moon. People today know that there are no underground cities on the moon. However, the question that the "moon people" asked is still an interesting one. A growing number of scientists are seriously thinking about it.

    Underground systems (体系) are already in place. Many cities have underground car parks. In some cities, such as Tokyo, Seoul and Montreal, there are large underground shopping areas. The "Chunnel", a tunnel connecting England and France, is now completed.

    But what about underground cities? Japan's Taisei Corporation is designing a network of underground systems, called "Alice Cities". The designers imagine using surface space for public parks and using underground space for flats, offices, shopping and so on. A solar dome (太阳能穹顶) would cover the whole city.Supporters of underground development say that building down rather than building up is a good way to use the earth's space. The surface, they say, can be used for farms, parks, gardens, and wilderness. H. G. Wells's "moon people" would agree. Would you?

The Vine That Ate the South

    Kudzu is a fast-growing vine(蔓生植物) that covers a large area in the southern United States. It is so common that one might think it is a native plant, but it is not. Kudzu was brought to the United States from Japan in 1876. Many Americans thought it was beautiful, and they began to plant it. They didn't know it could grow up to a foot a day during the summer months. Nor did they know it would grow up and over anything in its path.

    In Japan, kudzu experienced cold winters and a short growing season. But in the United States, it has a very long growing season with warm and wet southern weather. It is fine weather for the vine to grow fast.

    In the 1920s, people used the vine to feed farm animals. Ten years later, the government supported to plant kudzu because it kept soil from washing away. However, by the 1950s, the government no longer wanted people to plant the vine. Twenty years after that, the government said it was a harmful plant.

    The vine grows up trees and buildings, making some beautiful shapes. However, trees die after kudzu covers them because they cannot get enough light. Scientists are looking for ways to kill the vine. They used poisons(毒药) to kill the vine. However, some of the poisons made it grow even better. Scientists also find it difficult to dig up Kudzu. The plant is really tough.

    Because kudzu is so hard to kill, some people are making the best of it. So they try to find different uses for the vine. They find the vine can be used to make paper and baskets, it can be used to feed the goats, and it can even be eaten by people. Scientists are studying it in the hope that the vine can be used as a medicine. At the very least, kudzu serves as an example of the unexpected results that can come from non-native plants.

    We all cry for water when we are thirsty. But do you know, in very hot, dry weather, plants also make very low sounds as if they are crying for help?

    You see, in a plant's stem there are several hundred "water pipes" that bring water from soil all the way up to the leaves. When the ground turns dry, it becomes harder and harder for plants to do this.

    In very hot days, plants have to get any water that they can get.

    Scientists Robot Winter has found out that when plants can get no water, their "water pipes" snap(发出声音). When that happens, the whole plant vibrates(颤动) a little.

    Robot knows that healthy, well-watered plants are quiet. He also knows that dry plants are many insects' favorites and they often attack(袭击) them. How do the insects know which are healthy plants and which are not? Robot thinks that the insects may hear the plants "crying" and they may come to kill them.