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Passage One

Q.There's a lot of talk about putting up manned orbital stations. What does this mean, concretely? 

  • A. It is very important to have scientific stations in space. A space telescope. with a mirror slightly over six and a half feet in diameter will be placed in orbit,. and there will be more and more of these. A few years ago, our group at Saclay
  • A.Observation is much more precise beyond the atmosphere, because the sky is darker. You see many more stars and objects that are concealed by the earth's luminescence.     Q.What objects? 
  • A. We know pretty well how stars are born because we can observe them. Two or three new stars appear in our galaxy every year. But nearly all the galaxies were born at the same time, when the universe was constituted 15 billion (light) years ago
  • A. In 1989 the satellite Voyager II will reach Neptune after a journey of three and a half years. In addition, five probes were sent to rendezvous with Halley's comet. So exploration of the solar system is more or less under way. We'
  • But visiting the stars is something else again. Light takes four years to reach the nearest stars, so you can see that it would take a satellite hundreds of thousands of years.      Questions 1-5 are based on Passag
  • An orbital station is ____. 
  • A.a scientific laboratory in space
  • B.a collector of gamma rays
  • C.a space telescope in orbit
  • D.a celestial object
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It's early August and the countryside appears peaceful. Planting has long been finished and the fields are alive with strong, healthy crops. Soybeans and wheat are flourishing under the hot summer sun, and the com is now well over six feet tall. (46. Herds of dairy and beef cattle are grazing peacefully in rolling pastures which surround big. red barns and neat. white farmhouses. Everything as far as the eye can see radiates a sense of prosperity.)

The tranquility of the above scene is misleading. Farmers in the Midwest put in some of the longest workdays of any profession in the United States. In addition to caring for their crops and livestock, they have to keep up with new farming techniques, such as those for combining soil erosion and increasing livestock production.It is essential that farmers adopt these advances in technology if they want to continue to meet the growing demands of a hungry world.

(47.Agriculture is the number one industry in the United States and agricultural products are the country's leading export.Com and soybean exports alone account for approximately 75 percent of the amount sold in world markets.)

This productivity,however,has its price.Intensive cultivation exposes the earth to the damaging forces of nature.Every year wind and water remove tons of rich soil from the nation's croplands,with the result that soil erosion has become a national problem concerning everyone from the farmer to the consumer.

Each field is covered by a limited amount of topsoil,the upper layer of earth which is richest in the nutrient and minerals necessary for growing crops.In the 1830s,nearly two feet of rich,black top soil covered the Midwest.Today the average depth is only eight inches,and every decade another inch is blown or washed away. (48.A United States Agricultural Department survey states that if erosion continues at its present rate,corn and soybean yields in the Midwest may drop as much as 30 percent over the next 50 years.)

So far, farmers have been able to compensate for the loss of fertile topsoil by applying more chemical fertilizers to their fields;however,while this practice has increased crop yields, it has been devastating for ecology. (49.Agriculture has become one of the biggest polluters of the nation's precious water supply. River, lakes,and underground reserves of water are being filled in and poisoned by soil and chemicals carried by drainage from eroding fields. )Furthermore, fertilizers only replenish the soil; they do not prevent its loss.

Clearly something else has to be done in order to avoid an eventual ecological disaster.Conservationists insist that the solution to the problem lies in new and better farming techniques. (50.Concerned farmers are building terraces on hilly fields,rotating their crops,and using new plowing methods to cut soil losses significantly.Substantial progress has been made.but soil erosion is far from being under control.)

The problems and innovations of the agricultural industry in the Midwest are not restricted to growing crops.Livestock raising,which is a big business in the central region of the United States, is also undergoing many changes.

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