考满分 toefl

1 .Listen to part of a lecture in an earth science class.

听一段地球科学课上的讲座

1 .Professor: Although we've been keeping accurate climate records for maybe a few centuries, the field of paleoclimatology looks at the geological record to find out about the earth's climate in the distant past. We recently analyzed a stalagmite from a cave in western China that sheds some light on the relationship between global climate change and human society.

教授：尽管我们精确记录气候的时间可能也就几个世纪，但古气候学领域是通过研究地质记录来了解地球远古时期的气候状况。最近，我们分析了中国西部一个洞穴中的石笋，这为全球气候变化与人类社会之间的关系提供了一些线索。

1 .Professor: Now think of a stalagmite and think about how it forms, who can tell us how stalagmites are formed. Jenny?

教授：现在，大家想想石笋，思考一下它是如何形成的。谁能告诉我们石笋是怎么形成的？珍妮？

1 .Student: Sure. Stalagmites form when cave…when water drips down from the roof of a cave, there's like some sort of mineral in the water that gets deposited on the cave floor or something. Over thousands of years, the deposits build up.

学生：当然可以。石笋是当洞穴…… 当水从洞穴顶部滴落时形成的，水中好像含有某种矿物质，会沉积在洞穴底部之类的地方。经过数千年，沉积物不断堆积。

1 .Professor: That's right. Ground water carries minerals, mostly calcium and deposits them when it drips through a cave ceiling, resulting in a kind of layering of the deposits, that's the stalagmite. Now, much of China's weather in the southeast part of the country is affected by monsoon rains, the going through one rainy and one dry season each year. In the northwest, there's a more temperate, drier climate. And this particular cave we're talking about is located in a region between a monsoon and temperate climate. So, it's sensitive to drought years when less rain falls in the rainy season. So, stalagmites may grow faster or slower, depending on the amount of rainfall. More water means more growth. Max, question?

教授：没错。地下水携带矿物质，主要是钙，当水滴从洞穴顶部落下时，矿物质就会沉积下来，从而形成一种沉积物的分层，这就是石笋。中国东南部大部分地区的天气受季风降雨影响，每年都会经历一个雨季和一个旱季。在西北部，气候则更为温和、干燥。而我们所说的这个特殊洞穴位于季风气候和温带气候的过渡区域。所以，在雨季降水较少的干旱年份，它会很敏感。石笋的生长速度可能会因降雨量的不同而有所变化，水分越多，生长越快。马克斯，你有问题？

1 .Student: Don't all the stalagmites grow that way? What makes this one so important?

学生：所有石笋不都是这样生长的吗？这个石笋为什么如此重要呢？

1 .Professor: Its location. If it were squarely in a tropical monsoon climate, it probably wouldn't be affected so much by drought. Also, the ground in this area, the ground water isn't just seeping through calcium, but also through an unusually high concentration of uranium. Uranium is a radioactive element. So it decays at a predictable, regular rate. And the uranium is the reason that we can accurately date the stalagmite. So, this case has produced an extremely accurate climate record dating back 1,800 years.

教授：这和它的地理位置有关。如果它完全处于热带季风气候区，可能就不会受到干旱这么大的影响。而且，这个地区的地下水不仅会渗透过钙，还会经过浓度异常高的铀。铀是一种放射性元素，它会以可预测的、固定的速率衰变。正是因为铀的存在，我们才能精确测定石笋的年代。所以，这个石笋提供了一份可追溯到 1800 年前的极其精确的气候记录。

1 .Another thing researchers did was they checked the stalagmite against Chinese historical records. What they found was that there is a strong correlation between the climate, the rainfall that the stalagmite records and what was going on in society at the time. For example, when the stalagmite shows years of abundant rainfall, Chinese society was at peace and culturally productive. Times of drought seemed to have sped up, exacerbated social problems and probably led to the downfall of several Chinese dynasties. Jenny?

研究人员还做了另一件事，他们将石笋的记录与中国的历史记录进行了比对。他们发现，石笋记录的气候、降雨量与当时的社会状况之间存在很强的相关性。例如，当石笋显示出降雨充沛的年份，中国社会就会处于和平状态，文化也蓬勃发展。而干旱时期似乎会加剧社会问题，甚至可能导致了几个中国朝代的覆灭。珍妮，你有想说的吗？

1 .Student: Well, that makes sense, right? If there's abundant rainfall, there's lots of crops and everybody's happy. A drought would mean less food and increasing social strife. True?

学生：这很合理，不是吗？如果降雨充沛，庄稼就会丰收，人们都很幸福。而干旱意味着粮食减产，社会冲突加剧，对吧？

1 .Professor: This pattern wasn't just limited to ancient Chinese dynasties. There is evidence that when the Tang dynasty was in decline about 1,000 years ago, partially due to a prolonged drought, something similar was happening to classic Mayan civilization in what is now southern Mexico and Central America. Here we see...

教授：这种模式并不仅限于中国古代王朝。有证据表明，大约 1000 年前唐朝衰落时，部分原因是长期干旱，与此同时，在现在的墨西哥南部和中美洲地区，经典的玛雅文明也发生了类似的情况。在这里我们看到……

1 .Student: Wait, how could a Chinese drought affect Mayan civilization? Professor: It couldn't, not really, we think that something was affecting the climate in both China and the territory of the Mayans. We're trying to find out what could do that on such a global scale. And the stalagmite offers some clues. We found cyclical, wet, then dry periods throughout the stalagmite’s history, a cycle of about 11 years. Now, the neat thing about this seems to correspond with an 11-year cycle in the sun's activity. See, the sun goes through cycles of increasing and decreasing energy output. The peak years of solar activity tend to correspond to wet periods. And years of weak solar activity correspond to drier periods.

学生：等等，中国的干旱怎么会影响到玛雅文明呢？ 教授：实际上并不会，我们认为是某种因素同时影响了中国和玛雅地区的气候。我们正在试图找出在全球范围内能产生这种影响的因素。而这个石笋提供了一些线索。我们在石笋的生长历史中发现了周期性的湿润和干燥时期，周期大约为 11 年。有趣的是，这似乎与太阳活动的 11 年周期相对应。太阳的能量输出会经历增强和减弱的周期变化。太阳活动高峰期往往对应湿润时期，而太阳活动较弱的年份则对应干旱时期。

1 .Student: So, the sun ruined ancient civilizations? Professor: Well, not exactly. You see, the prevailing theory is that in times of decreased solar activity, less ocean water evaporated at the equator, which means less moisture in the atmosphere that could fall as rain. So, there was a dry period. In this case, in China during the downfall of the Tang dynasty. But keep in mind what we're talking about the link between potential global climate change and ancient civilizations decline. It's just too complex for a simple cause-effect relationship. We are discussing a single piece of evidence from one cave in a very large continent. Climate probably played a role, but we don't know how much of a role.

学生：所以，是太阳导致了古代文明的衰落吗？ 教授：也不完全是。主流理论认为，在太阳活动减弱的时期，赤道地区的海水蒸发量减少，这意味着大气中可形成降雨的水汽减少，进而导致干旱。在唐朝衰落的时候，中国就处于这样一个干旱期。但要记住，我们讨论的是潜在的全球气候变化与古代文明衰落之间的联系。这太过复杂，不是简单的因果关系。我们只是在讨论来自一个大洲上一个洞穴的单一证据。气候可能起到了一定作用，但我们不知道作用有多大。