『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 5 Lec 3听力练习：What is the main purpose of the lecture?原文题目答案解析，TPO/Official 5 Lec 3听力原文范文音频翻译。

托福TPO/Official 5 Lec 3听力原文What is the main purpose of the lecture?-新东方托福官方网校手机版

独白：请听化学课上的一篇演讲

Narrator: Listen to part of a lecture in a chemistry class.

教授：好的，我知道你们对此次的实验作业都有很多问题，

Professor: Okay. I know you all have a lot of questions about this lab assignment that's coming out so ...

因此今天早上我将花点时间跟你们讨论一下。

I'm gonna take a little time this morning to discuss it.

那么，你们知道此次作业是跟光谱学有关的，是吧？

So, you know the assignment has to do with Spectroscopy, right?

你们通过阅读应该能够很好了解这个概念。

And your reading should help you get a good idea of what that's all about.

但是，我们还是将一些基本要点过一遍吧。

But, let's talk about Spectroscopy a little now just to cover the basics.

嗯，我能给你们的最简单的定义就是，光谱学是关于物和光之间相互作用的研究。

Well, the simplest definition I can give you is that Spectroscopy is the study of the interaction between matter and light.

这样，可见光拥有不同颜色和波长，聚在一起就成了我们做说的光谱。光谱是一条五颜六色的缎带，就像你看到的彩虹一样。

Now, visible light consists of different colors or wavelengths, which together make up what's called spectrum, a band of colors, like you see in a rainbow.

而所有的物质和物质形式都可以根据其吸收的光的波长和其反射的光来加以区分。

And all substances, all forms of matter, can be distinguished according to what wavelength of light they absorb and which ones they reflect.

它就像，嗯，什么元素都有，我们所说的，它本身的光谱签名。

It's like, um, well, every element has, what we call, its own spectral signature.

如果我们可以读懂，我们就可以知道是什么元素。

If we can read that signature, we can identify the element.

And that's exactly what spectroscopy does.

激光光谱学是你们作业中的重点，它能非常精确地测量光谱中哪一部分被不同的物质吸收。

Now, Laser Spectroscopy, which is the focus of your assignment, works by measuring very precisely what parts of the spectrum are absorbed by different substances.

该门学科在不同学科中有所应用。

And it has applications in a lot of different disciplines.

你们的任务就是要选择一门你感兴趣的学科然后进行实验。

And your assignment will be to choose a discipline that interests you, and devise an experiment.

比如说，我要谈谈关于艺术这门课。

我对艺术很有兴趣，我对光谱学是怎么应用在对艺术的分析上的问题感兴趣。呃……

I'm interested in the art and to me it's interesting how spectroscopy is used to analyze art.

比如一位博物馆馆长带着问题走向你。

Let's say a museum curator comes to you with a problem.

比如说，她碰到一幅貌似是真迹的油画，出自伦勃朗之手。

She's come across this painting that appears to be an original - let's say, a Rembrandt.

她想收购这幅画放到博物馆中去。

And she wants to acquire it for her museum.

但她有一个问题：她不是很确定这是否为真迹。

But she's got a problem: she's not absolutely certain it's an original.

How do you determine whether the painting's authentic?

Okay. Think about the scientific process.

你现在的问题是：这幅画是伦勃朗画的吗？

You've got the question: Is the painting a Rembrandt?

那么首先，你将需要列出伦勃朗画作具有的特征。

So first, you'll need to make a list of characteristics the painting would have to have to be a Rembrandt.

然后你必须看这幅有争议的画是不是有这些特征。

Then you have to discover whether the painting in question has those characteristics.

首先，你要了解伦勃朗在帆布上画画时会使用的技巧，他的画风，他用的颜料的情况。

So first of all, you'll need to know the techniques Rembrandt used when he applied paint to canvas - his brushstrokes, how thickly he applied his paint.

那么你要请教一名对伦勃朗画风有专业了解的艺术历史学家。

So you'd need to work with an art historian who has expert knowledge of Rembrandt's style.

你要知道他什么时候创作，嗯，用什么颜料创作，换句话说，就是他使用什么材料画出不同的颜色，因为绘画中使用的颜料和粘合剂会随着时间而改变。

You'd have to know when he created his paintings, um... what pigments he used, in other words, what ingredients he used to make different colors of paint, cause the ingredients used in paints and binding agents plus burnishes, finishes, what have you, have changed over time.

由于你试图证明这是伦勃朗的真迹，其颜料中使用的材料就必须是伦勃朗那个年代，即十七世纪，所使用过的颜料。

Since you're trying to verify if it's a Rembrandt, the ingredients in the pigment would need to have been used during Rembrandt's lifetime - in the 17th century.

你要了解颜料的成分，而这需要做实验，探测性实验，才能得知，这就是光谱学。

You've got to find out what's in those pigments, learn their composition, and that requires lab work - detective work really - in a word, Spectroscopy.

嗯，我们使用红外线显微镜，一个分光镜，来观察油画上很小很小的部分。

Well, we put an infrared microscope - a spectroscope - on tiny tiny bits of paint.

使用紫外线，我们可以看到颜料上每一部分的光谱特征。

And using ultraviolet light we can see the spectral signature of each component part of the pigment.

然后我们将这些特征和一些特别的元素，锌和铅，来判定颜料是什么组成的。

Then we compare these signatures with those of particular elements like zinc or lead, to determine what the pigment was made of.

这样，你就知道为什么这种研究需要关于颜料使用史的知识了对吧？

So, you can see why this type of analysis requires a knowledge of the history of pigments, right?

比如我们判定某一种颜料是由锌构成的。

Say we determined a pigment was made with zinc, for example.

我们也知道直到18世纪锌才被发现。

We also know that zinc wasn't discovered until the 18th century.

而伦勃朗生活在十七世纪，我们知道他是不可能用锌来作画的。

And since Rembrandt lived during the 17th century, we know he couldn't have painted it.

现在，光谱学比起以前的解析作品的方法优异更为明显，因为它不不会对原作造成损害。

Now, Spectroscopy has a very distinct advantage over previous methods of analyzing our works, because it's not invasive.

你不需要移动一部分油画来进行分析，而其他方法是必须的。

You don't have to remove big chips of paint to do your analysis, which is what other methods require.

你所做的就是；练习使用显微镜对准油画上的小小斑点，进行分析。

All you do is to train the microscope on tiny flecks of paint and analyze them.

有时候艺术品真迹看起来是赝品是因为很多修护人员加上很多层保护膜覆盖油画上的损害。画作上损坏的地方经久日衰。

Sometimes original art works appear questionable or inauthentic because they've had so many restorers add touch-up layers to cover up damage, damage from the paint having deteriorated over time.

而光谱学也可以检查这一层附加上去的物质成分。

Well, spectroscopy can reveal the composition of those touch-up layers too.

我们因此可以知道是什么时候加上去的一层东西。

So we can find out when they were applied.

而如果我们想避免一些错误的修复尝试，我们能通过判定修复过程中哪一步会溶解画作和掩盖真迹的痕迹。

Then if we want to undo some bad restoration attempts, we can determine what kind of process we can use to remove them to dissolve the paint and uncover the original.

What does the professor imply when he mentions an art historian?

Why does the professor discuss the presence of zinc in paint pigments?

According to the professor, what is the primary advantage of spectroscopy over other laboratory methods for analyzing artworks?

What is one way the professor mentions that chemists can help with art restoration?

Narrator 
Listen to part of a lecture in a chemistry class. 
Professor 
Okay. I know you all have a lot of questions about this lab assignment that's coming out so ... I'm gonna take a little time this morning to discuss it. So, you know the assignment has to do with Spectroscopy, right? And your reading should help you get a good idea of what that's all about. But, let's talk about Spectroscopy a little now just to cover the basics. 
What is Spectroscopy? Well, the simplest definition I can give you is that Spectroscopy is the study of the interaction between matter and light. Now, visible light consists of different colors or wavelengths, which together make up what's called spectrum, a band of colors, like you see in a rainbow. And all substances, all forms of matter, can be distinguished according to what wavelength of light they absorb and which ones they reflect. It's like, um, well, every element has, what we call, its own spectral signature. If we can read that signature, we can identify the element. And that's exactly what spectroscopy does. 
Now, Laser Spectroscopy, which is the focus of your assignment, works by measuring very precisely what parts of the spectrum are absorbed by different substances. And it has applications in a lot of different disciplines. And your assignment will be to choose a discipline that interests you, and devise an experiment. 
For example, I'm gonna talk about art. I'm interested in the art and to me it's interesting how spectroscopy is used to analyze art. Let’s say a museum curator comes to you with a problem. She's come across this painting that appears to be an original - let's say, a Rembrandt. And she wants to acquire it for her museum. But she's got a problem: she's not absolutely certain it's an original. So, what do you do? How do you determine whether the painting's authentic? 
For example, I'm gonna talk about art. I'm interested in the art and to me it's interesting how spectroscopy is used to analyze art. Let’s say a museum curator comes to you with a problem. She's come across this painting that appears to be an original - let's say, a Rembrandt. And she wants to acquire it for her museum. But she's got a problem: she's not absolutely certain it's an original. So, what do you do? How do you determine whether the painting's authentic? 
Okay. Think about the scientific process. You've got the question: Is the painting a Rembrandt? So first, you'll need to make a list of characteristics the painting would have to have to be a Rembrandt. Then you have to discover whether the painting in question has those characteristics. 
So first of all, you'll need to know the techniques Rembrandt used when he applied paint to canvas - his brushstrokes, how thickly he applied his paint. So you’d need to work with an art historian who has expert knowledge of Rembrandt's style. You'd have to know when he created his paintings, um... what pigments he used, in other words, what ingredients he used to make different colors of paint, ‘cause the ingredients used in paints and binding agents plus burnishes, finishes, what have you, have changed over time. 
Since you're trying to verify if it’s a Rembrandt, the ingredients in the pigment would need to have been used during 
Rembrandt's lifetime - in the 17th century. And that's where chemistry comes in. You've got to find out what's in those pigments, learn their composition, and that requires lab work - detective work really - in a word, Spectroscopy. So, how do we use Spectroscopy? 
Well, we put an infrared microscope - a spectroscope - on tiny tiny bits of paint. And using ultraviolet light we can see the spectral signature of each component part of the pigment. Then we compare these signatures with those of particular elements like zinc or lead, to determine what the pigment was made of. So, you can see why this type of analysis requires a knowledge of the history of pigments, right? How and when they were made? Say we determined a pigment was made with zinc, for example. We know the spectral signature of zinc. And it matches that of the paint sample. We also know that zinc wasn't discovered until the 18th century. And since Rembrandt lived during the 17th century, we know he couldn't have painted it. 
Now, Spectroscopy has a very distinct advantage over previous methods of analyzing our works, because it's not invasive. You don't have to remove big chips of paint to do your analysis, which is what other methods require. All you do is train the microscope on tiny flecks of paint and analyze them. 
Now a word or two about restoration. Sometimes original art works appear questionable or inauthentic because they’ve had so many restorers add touch-up layers to cover up damage, damage from the paint having deteriorated over time. Well, spectroscopy can reveal the composition of those touch-up layers too. So we can find out when they were applied. Then if we want to undo some bad restoration attempts, we can determine what kind of process we can use to remove them to dissolve the paint and uncover the original. 
Now a word or two about restoration. Sometimes original art works appear questionable or inauthentic because they’ve had so many restorers add touch-up layers to cover up damage, damage from the paint having deteriorated over time. Well, spectroscopy can reveal the composition of those touch-up layers too. So we can find out when they were applied. Then if we want to undo some bad restoration attempts, we can determine what kind of process we can use to remove them to dissolve the paint and uncover the original.