最新学术综合英语听力原文完整版Word格式.docx

1、Unit 1 Presenting a SpeechRoad BuildingGood morning, everyone. Today Ill be talking about the relationship between road building and the development of the American economy during the 18th century. About 300 years ago, the United States economy was growing rapidly, mainly because of a booming trade

2、in two important agricultural products: grain and cotton.Grain output in the eastern part of America increased quickly at that time due to the rapidly growing population and the large number of immigrants from Europe. As a result, the demand for grain almost doubled. For this reason, the trade in gr

3、ain first developed in this part of the country. At the same time, the road system was gradually built up in order to transport the grain from the rural areas to various cities. The road building clearly helped develop the economy quickly in these areas and in the cities as well.During the same peri

4、od, farmers in the South could get a large amount of laborers from Africa, and they started to grow cotton. As the cotton output increased, the farmers needed to sell it in other places. As a result, many roads were built to link the rural areas to the cities.At first, this trade of grain and cotton

5、 took place along the coast, or near rivers and lakes. It took place there because it was easy and cheap to transport goods from one place to another. Before 1700, it was very expensive to move the goods by road. So, farmers had to rely mainly on rivers to move their crops to markets.At that time, t

6、here was only one continuous road that existed in the US. It ran from north to south along country roads, which were 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

7、 from all vehicles that traveled on them.Eventually, because of the booming trade of grain and cotton, a network of roadways was completed that connected some major cities and towns. Although traveling was still costly for farmers, they soon preferred to move their crops to cities and other areas on

8、 roadways rather than by boat because it was faster and more convenient.So here we can see a rather clear picture of road building in the United States and its impact on economic development during that period.The Mississippi River in AmericaGood afternoon. Today were going to talk about the Mississ

9、ippi River. The Mississippi River is the largest river of the North America. Its major tributaries drain an area of approximately 3,000,000 square kilometers, or about one-eighth of the entire continent. The Mississippi River lies entirely in the United States. From its source at Lake Itasca in Minn

10、esota, it flows from the North almost due south across the continental interior, collecting the waters of its major tributaries, down to the Gulf of Mexico.The Mighty Mississippi, as it is affectionately known, flows a total distance about 4,000 kilometers from its source. With its tributaries, the

11、Mississippi drains all or part of 31 U.S. states and two Canadian provinces.As everyone knows, in the past the river was the most important way of transporting goods from the North to the South, or from the South to the North in the United States.The Mississippi River is also a river that can someti

12、mes get out of control and cause serious flooding in summer. Nowadays engineers use four different methods to control the floodwaters of the river. These four ways are: flood ways,dams, levees and reservoirs. Ill discuss each of these here.Floodways are the first way of controlling the floodwaters o

13、f the Mississippi River. Floodways are empty channels ready to hold water from the river. When the Mississippi River is too high, the floodways are opened and some of the water can flow into the floodways. There are several floodways along the lower Mississippi River, which help prevent flooding eff

14、ectively.The second way of controlling the floodwaters of the Mississippi River is with dams. Dams are walls that are built across a river to control the water. There are more than 30 dams on the Mississippi River. Dams control the water by holding the water behind them until a decision is made to r

15、elease it.Levees are a third way of controlling the floodwaters of the Mississippi River. Levees are earthen walls built alongside a river. They hold the water in the river and keep it from covering the land beside the river. There are more than 2,000 miles of levees along the Mississippi River.In t

16、he 19th and 20th centuries, several reservoirs were built along the Mississippi River to harness the water. They have two functions. One is to hold water, and the other is to generate electricity through hydroelectric power stations. Since the 20th century, no huge flood has broken out of the Mississippi River.Unit 2 Energy ConservationAn Eyewitness to Changes in China（Y: Yang Rui, anchor of Dialogue, CCTV-9R: Sidney