托福听力每日一练第39天：（2003年10月）
演讲听写训练1：
Today, we are going to talk about a special way some plants respond to being invaded by pests. These plants react by emitting a chemical signal, which acts like a call for help. Let’s take corn plants for example. Sometimes, caterpillars chew on the corn leaves. When the caterpillar saliva mixes with the chew portion of a leaf, the plant releases a chemical scream that attracts wasps. The wasps respond to the signal by flying to the chewed-on leaf, and laying their eggs in the caterpillars. The caterpillars die in the next few days as the wasp offspring nourish themselves by feeding off them. Thus the corn plant prevents all its leaves from being eaten by the caterpillars. This chemical scream is specific. It’s only released after the plant has detected the caterpillar saliva. A plant that is cut by any other means does not give off the same signal, nor doesn’t undamaged plant. This also explains how a wasp can find a caterpillar in a huge field of corn. Soybeans, cotton and probably many other plants use a similar type of defense against pests. By enhancing this natural response in plants, researchers might reduce, or some day even eliminate, the need for chemical pesticide, which can cause ecological damage. For example, scientists might breed plants for this screaming trait, or they might transplant specific genes to increase the release of chemical signals.
演讲听写训练2：
Today, we are going to continue our discussion of Buddhism. In our last class, we talked about how it’s practiced. Today, I’d like to talk a little about early Buddhism, which we really don’t know much about. Well, what is known is that the teachings of Buddhism were memorized, and passed on orally for centuries by its followers. Recently, there was an important discovery of Buddhist manuscripts that are believed to be the oldest ever found. They may be 2,100 years old. And there maybe as many as 20 of them. It’s expected that we will be able to learn from them about the spread of Buddhism from present day India into China, and throughout Asia. But the scrolls themselves have presented challenge too. They were very fragile, found rolled up in clay pots. Before they even could be looked at, they need to be dampened over night in fact, and then carefully flattened with tweezers. And it’s not that anybody could just sit down and read them. The scrolls were written in a language that is really rare today. Only a few people are proficient at it. Considering these challenges, it’s easy to understand why it’s taken scholars so long to examine the scrolls.
演讲听写训练3：
About 200 years ago, the United States economy was growing quickly, mainly because a booming trade in grain and cotton. This trade in grain and cotton went on near areas near or at the coast, or near navigable rivers. It took place there because it was so expensive to transport goods over the roads that existed. They were muddy, narrow, and hard to travel on. At that time, don’t forget there was only one continuous road that existed in the US, and it was made up of north to south local country roads, linked together to make one long road. Within a short time, the first east-to-west roads were built. They were called turnpikes. Private companies built these roads, and collected fees from all vehicles that traveled on them. Eventually, a network of dirt, gravel or plank roadways connected some major cities and towns. But even these turnpike roads were still very slow, and traveling on them was too costly for farmers. They would’ve spent more money to move their crops than they got by selling them. So, we see that even with some major improvement in roadways, farmers still had to rely on rivers to move their crops to market.
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