托福听力lecture并列型分析

之前我们介绍了lecture的并列型结构，一般是围绕某一个主题并列平行展开去讲解。这类结构没有之前我们见到的直线型结构那么好区分，因为他没有明显的表示时间地点人物的信号词，但是这种结构类型是我们TPO和考试中出现的比较多的结构类型。我们这次分析一篇按并列结构分层的一篇文章。

今天我们以TPO33-L2为例，给大家讲解一下。

I’d like to continue with the topic of managing water resources, but I want to focus on a particular case. Uh, um, an example of water management that’s made us reconsider the methods we use when we make these decisions. So let’s look at what’s happening in the Colorado River basin. 这篇文章主要要讲到的是管理水资源，并且举了一个具体的例子Colorado River basin。

The Colorado River basin is a region in the Southwest United States. Seven states rely on the Colorado’s water. And as you can imagine, as the populations of these states began to grow, it became clear that a system to distribute, uh, to make sure each state got its fair share of water…some kind of system had to be created. And in 1922, a water-sharing agreement was made. Elizabeth, you have a question?

Student

Well, how exactly do you figure out how to share a river? I mean, you can’t…like cut it up into pieces.学生首先提出一个问题：我们如何去分一条河呢，河也不能被切开啊

Professor

Well, let’s start with the first step. And that’s trying to figure out how much water on average flows through the river each year. Now, researchers had started gathering data on water flow back in the late 1890s using instruments they placed in the river. When the 1922 water-sharing agreement was made, there were about twenty years of data on water flow available. The average annual flow was calculated. And, well, the agreement was based on that calculation. The same basic agreement is in effect today. 老师回答这个问题之前先提出了一个问题：我们如何确定一条河的流量呢?确定了流量才能考虑河流的分配

Student

Wait! That was all the data they had? And they based their decision on that?这个地方学生明显表现出了自己的态度：觉得这个数据是有问题的

Professor

Yes. And we’ll why that was a bad decision in a moment. 老师也直接表明了学生的想法是对的，这确实是一个不好的决定。OK. As decades passed, it became clear that measuring river flow was much more complicated than we had thought. See…a river has periods of low flow and periods of high flow. And this wasn’t taken into consideration when the 1922 agreement was made. In the 1970s, the population of the area was rising while the amount of water flowing through the river seemed to be falling. By this time, we had…what? A hundred years of recorded data to look at? That’s still a pretty short time for an ancient river. 随着时间的推移，我们有了更多的数据，积累了100年的数据，但是这还是不足够的。

To get more data, we looked at a different source—a source that was able to tell us about hundreds of years of the river’s history—tree rings. OK. Let me explain.

You probably know that we can determine a tree’s age by counting the rings on a cross section of its trunk. Each ring represents one year of the tree’s life. So if you know the year the tree was cut, you can count inwards and date each ring all the way back to the center. You can also tell how much moisture the tree got during each of those years by looking at the width of the rings. A wide ring means plenty of water while a narrow one indicates less. 那么既然这些数据都不够，我们就要想另一种方式去测量，得出更准确的结论。这就是使用年轮，我们都知道年轮能够记录树的年龄，但是我们不知道的是年轮还可以测量每年的水量。这就能够告诉我们很多我们之前不知道的信息

Fortunately for us, certain areas of the Colorado River basin are home to some very old trees, some 800 years old and older. Researchers can drill core samples, uh, basically get a cross section of a tree without having to kill it, look at the rings and get a picture of what the climate was like in the basin for each of the tree’s years.

Well, the results tell us something we wouldn’t have known without this data, that over the past 500 years or so, the Colorado River basin has experienced severe droughts, some worse than any we’ve ever recorded. They also showed that the early to mid-1900s, when most of the data that led to the water-sharing agreement was collected…well, this was the wettest period in the past 400 years. Well, obviously, had water management officials known then what we know now, the 1922 agreement would have been handled differently. 并且幸运的是，这个区域有一些非常古老的树，我们就能判断出来，这个区域在过去的500年间其实都是非常的干燥的，而仅仅就在1922年这几年的雨量较大而已，所以科学家当时所做的估测都是不合理的。

But today we can use the past to help prepare us for the future. With the demand for water in the basin stays increasing and with the real likelihood of lower flows in the river, if history is our teacher, we can develop innovative methods of water conservation and reevaluate how water is distributed.  现在我们有了这个技术，科学家们也就更加的自信，我们在未来能够更好的去测量水量，从而更好的分配水源。

的并列型结构的这篇文章就给大家分享到这里，新通教育为大家提供课程，如果同学们在复习当中效率不高，可以考虑通过参加的方式来提升复习效率，提高。当然如果同学们对还有任何疑问，

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