托福听力TPO文本32
TPO32
Conversation 1
Listen to a conversation between a student and a bookstore employee.
Employee
Hi. Can I help you?
Student
Yeah. I need to sell back a textbook. Are you the person I speak to about that? Employee
I am. But we can’t buy textbooks back just yet, because the bookstore’s buyback period isn’t until next Thursday.
Student
I thought it started this week.
Employee
It is only in the last week of the semester after classes are over.
Student
Oh. Well, can you tell me if this book will be on the buyback list?
Employee
I can look. But we are still putting the list together. Professors have to tell us what books they’ll definitely need again next semester, and the deadline for them to let us know isn’t for a couple of days. So the list I have here is not really complete. Um…what class was the book for?
Student
Intro to economics, with Professor Murphy.
231
Employee
Professor Murphy. OK. I checked earlier and I know she hasn’t gotten back to us on that class yet. So we don’t know if she’ll use the same book next time. Usually if an updated edition of a textbook is available, professors will go for that one.
Student
Um…so if this book doesn’t end up on the buyback list, what can I do? I spent over a hundred dollars for it, and I want to get something back.
Employee
Well, if a professor didn’t assign it for a class here, we could buy back for a whole seller who would distribute it for sale at another university bookstore.
Student
OK.
Employee
Anyway…if Professor Murphy does put it on the list, it is important that you come in
as early as possible next Thursday. There’s only a limited number of books we would buy back. Once we get the number of books we need for next semester, we would stop buying them.
Student
OK. So how much money will I get for the book?
Employee
Well, if it’s on the buyback list, we’ll pay fifty percent of what the new price was. But that also depends on what condition the book is in, so it needs to be cleaned up as
much as possible.
Student
Cleaned up?
Employee
Because used books show wear and tear, you know, water stains, scruffy covers,
yellow highlighting…You really need to make sure there are no pencil marks on the book. The price you can get for a text depends on the shape it’s in.
Student
You mean I have to erase all the pencil marks?
Employee
If you want the best price for it…
Student
And what if you decide the book is too beat-up and don’t buy it back?
Employee
That does happen. Hmm…well, one more thing you can try is to place an ad in the student newspaper to see if you can sell it directly to another student.
Lecture 1
Archaeology (Bananas & African History)
Listen to part of a lecture in an archaeology class.
Professor
One of the important aspects of the field of archaeology…one of the things that
excites me about the field…is that seemingly insignificant things can suddenly change the way we think about a culture. We are always making new discoveries that have the potential to challenge widely held beliefs.
Take something like the banana, for example. It turns out that this ordinary fruit may
be forcing scientists to rewrite major parts of African history! We know the bananas were introduced to Africa via Southeast Asia. And until recently, we thought we knew when they were introduced—about 2,000 years ago. But discoveries in Uganda, that’s in Eastern Africa, are throwing that into question. Scientists studying soil samples
there discovered evidence of bananas in sediment that was 5,000 years old!
Now, let me explain that it’s not easy to find traces of ancient bananas. The fruit is soft and doesn’t have any hard seeds that might survive over the ages. So after 5,000 years, you might think there would be nothing left to study. Well, fortunately for archaeologists, all plants contain what are called phytoliths in their stems and leaves. Phytoliths are microscopic structures made of silica, and they do not decay. When plants die and rot away, they leave these phytoliths behind. Because different plants produce differently shaped phytoliths, scientists can identify the type of plant from ancient remains.
So, those scientists in Uganda, dug down to sediments that were 5,000 years old. And what do you think they found? Banana phytoliths! Obviously this meant that we had to rethink our previous notions about when bananas first arrived in Africa. But, well, this discovery had other implications for history.
As soon as bananas appear in the archaeological record, we know we have contact between Africa and Southeast Asia. It would appear now that this contact occurred much earlier than previously thought.
Al…although…now here’s where the uncertainty comes in…we don’t really have any solid evidence of trade between the peoples of these two regions that long ago. Presumably, if people were bringing bananas to Africa, they’d also be bringing other things too: pottery, tools…all sorts of objects made for trade or daily use. But any such evidence is missing from the archaeological record.
The early appearance of bananas also suggests that agriculture began in this part of Africa earlier than scientists imagined. You see, bananas, at least the edible kind, can’t grow without human intervention. They have to be cultivated. People need to plant them and care for them. So if bananas were present in Uganda 5,000 years ago, we would have to assume…that…that…that someone planted them. The above text is a transcript of this lecture prepared by lady&bird (QQ).
But, there are questions about this too. We know that bananas can be a staple food that can support large populations, as they did in Uganda in the more recent past. If bananas were grown thousands of years ago, why don’t we see evidence of large populations thriving in the area earlier?
So, we are left with this mystery. We have what appears to be strong biological evidence that bananas were being cultivated in Uganda as early as 5,000 years ago.
But we are missing other kinds of evidence that would conclusively prove that this is so.
Clearly, more research needs to be done. Perhaps by some young scholar from this university? At least give it some thought.
Lecture 2
Biology (Populations in an Ecosystem)
Listen to part of a lecture in a biology class.
Student
Professor, since we are going to talk about changes in animal populations in the wild, I’d like to ask about something I read in an article online, about how the population size of some animal species can affect other animal species, and how other environmental factors come into play too.
Professor
Right. Relationships between animal species in a given ecosystem can get pretty complex. Because in addition to predator-prey relationships, there are other variables that affect population size.
Student
The article mentioned that populations of predators and their prey might go up rapidly and then decline all of a sudden.
Student
Oh. Yeah! I read about that in my ecology class. It happens in cycles. I think that’s called a boom-and-bust cycle. Right?
Professor
OK. Well, hold on a second. First I want to go over some key concepts. Let’s say there was a species that had access to plenty of food and ideal conditions. Under those circumstances, its population would increase exponentially, meaning it would increase at an ever-accelerating pace.
Student
Wow! That sounds a little scary.
Professor
Well, it doesn’t usually happen. Like you said, a rapid population growth is often followed by a sudden decline. But we do occasionally see exponential growth in nonnative species when they are transplanted into a new environment. Um…because they face little competition and have favorable growing conditions.
But for most species, most of the time, resources are finite. There’s only so much available…which leads me to my point. Every ecosystem has what we call a carrying capacity. The carrying capacity is the maximum population size of a species that can
be sustained by the resources of a particular ecosystem. Resources are, of course, food, water, and just as important, space.
Although every species has a maximum rate at which the population of that species could increase, assuming ideal conditions for the species in its environment. There are always going to be environmental factors that limit population growth. This is called environmental resistance. Environmental resistance is important because it stops populations from growing out of control. Factors such food supply, predation and disease affect population size, and can change from year to year or season to season. Student
OK. I think I get it.
Professor
Well, let’s look at a case study. That should make things clear. Some years ago, some of my colleagues conducted an experiment in an oak forest involving three different species: white-footed mice, gypsy moths and oak trees.
OK. Now let me explain what the situation is in this forest. Oak trees produce acorns, and acorns are a primary food source for white-footed mice. Another food source for
the white-footed mice is the gypsy moth. So the size of the gypsy moth population is controlled by the white-footed mice, which is a good thing because gypsy moth caterpillars are considered pests. They strip away the leaves from the oak trees every ten years or so.
Student
So the mice eat both acorns from the oak trees and gypsy moths. And the gypsy moth caterpillars eat oak tree leaves.
Professor
Right. Now, what makes this set of relationships particularly interesting is that oak trees only produce a large number of acorns every few years.
Student
So during the years with fewer acorns, the white-footed mice have to deal with a smaller food supply.
Professor
Yes. But in the years with large amounts of acorns, the mice have more food, which leads to…?
Student
The white-footed mice population growing.
Professor
And the gypsy moth population decreasing.
Student
How can we know that for sure? It seems like a big jump from more acorns to fewer gypsy moths.
Professor
Well, we can know for sure because in this oak forest, the researchers decided to test the links between acorns and the two animal species. In some parts of the forest, they had volunteers drop a large number of extra acorns on the forest floor. And in another section of the forest, they removed a number of white-footed mice. In the forest areas where extra acorns had been dropped, the gypsy moth population soon went into a significant decline. But in the section of the forest where the white-footed mice had been removed, the gypsy moth population exploded
Conversation 2
Listen to a conversation between a student and an anthropology professor. Professor
So how was the field trip to the Nature Center yesterday? You are in that biology class, aren’t you?
Student
Yeah. I am. The trip was amazing. We took a hike through the woods and our guide pointed out all kinds of animal and plant species. She could identify every bird, every tree…I have to tell you. I was very impressed with her knowledge.
Professor
I am glad to hear you enjoyed the trip.
Student
Well, I am interested in getting an advanced degree in forestry after I graduate from here. So I love all this stuff. And actually, yesterday’s trip got me thinking about my research paper for your class.
Professor
Wonderful! Tell me more.
Student
So our guide was talking about how the human need for resources had shaped the environment. And I just assumed that the human impact on the environment was always destructive.
Professor
Ah…but that’s not necessarily true.
Student
Yeah. That’s what she was telling us. She said there’s archaeological evidence that some prehistoric cultures relied heavily on dead wood for fuel, or…um…just cut off some of the branches of trees instead of killing the whole tree.
Professor
It is so funny you mentioned that. I was just reading an article about an archaeological site in Turkey where scientists found evidence that ancient people had been harvesting the branches from pistachio and almond trees.
Of course, when you prune
these trees, cutting off just the branches like that, you are actually encouraging more growth! And you end up with a bigger crop of nuts. So this was a pretty smart strategy
for collecting wood.
Student
See, that’s what I’d like to write about. I want to look at ancient methods of wood harvesting that didn’t result in the destruction of the whole forest.
Professor
Hmm…so you want to write your entire paper on wood harvesting?
Student
Is…is that a problem?
Professor
Well, it’s certainly a timely topic. Researchers are investigating this now. Uh…it’s just that…well…I am not sure how it fits with the assignment. Remember you are supposed to be focusing on a particular culture or region.
Student
Yeah. Um…actually I was planning on writing about the wood harvesting practices of the people who lived here. You know, the Native Americans who were living in this
area and what that might tell us about how they lived.
Professor
OK. Well, that’s a possibility. I just want to make sure you can find enough information on that topic to write a well-developed paper. I’d like you to get started on your research right away. Maybe even talk to that nature guide and show me what information you can find. Then we can talk about whether or not your topic will work.
Lecture 3
Earth Science (the Copper Basin)
Listen to part of a lecture in an earth science class. The professor is discussing an area
of the United States called the Copper Basin.
Professor
Now, you may not have heard of the Copper Basin. It’s in the Eastern United States, in the Tennessee River Valley. It got its name because settlers discovered copper there in 1843. And soon afterwards, it supported one of the largest metal mining operations in America. At one time, four mining companies employed 2500 workers in the Copper
Basin. For that time period, it was a huge operation.
Well, this mining operation turned the Copper Basin into a desert. In the 1840s, when mining operations started, it was a dense green forest. But in the 1940s, 100 years later, it was as barren as the moon.
Efforts to reclaim the land and restore the basin to the fertile valley it once was…well, actually, those efforts are still ongoing. It’s been a long and tedious process. In fact, it was many years before any results were seen. Copper mining had gone on there for more than 90 years! The damage couldn’t be reversed overnight.
Although I should mention that by 1996, the water in one of the rivers flowing through the basin was clean enough that it was the site of the Olympic whitewater kayaking competition. And that river is still used now for recreation.
But…anyway…let’s analyze the problem. It wasn’t the mining itself that caused such massive destruction. It was what happened after the copper ore was extracted from the mines. It was a process called heap roasting.
Copper ore contains sulfur. And heap roasting was a way to burn away the sulfur in the copper, so they’d be left with something closer to pure copper. Well, in the process, large vats of raw copper ore are burned slowly, for two or three months actually, to lower the sulfur content. And this burning, well…let’s look at the results.
First, the mines were fairly remote, so there was no way to bring coal or other fuel to keep the fires going. So they cut down local trees for fuel. And like I said, the fires burned for months. Uh…that’s a lot of fires and a lot of trees. Deforestation was occurring at a rapid rate. And it was accelerated by the smoke from the burning ore.
Big clouds of sulfuric smoke, which was toxic to the trees, formed over the areas. Trees that hadn’t been cut for fuel were killed by the fumes.
The sulfur also mixed with the air and created sulfur dioxide. And the sulfur dioxide settled in the clouds fell to the land in droplets of rain and sank into the soil. This is what we now call acid rain. You’ve probably heard of it. But no one used the term back then. Anyway…the acid rain created highly acidic soil. Well, soon the soil became so acidic that nothing could grow, nothing at all. Vegetation and wild life disappeared.
And it wasn’t just the land and the air, it was the water too. What do you think happen to the rivers? Well, there are no trees to absorb the rain, and there was a lot of rain! So
the rain eroded the soil and swept it into the rivers. This is called silting, when soil particles are washed into the rivers. And the silting continued at an alarming rate. But this was toxic soil and toxic runoff, the acid and metals in the soil made the once clear rivers flow bright orange.
So it was really that one step in the process of producing copper…the problems just built up and up until there was a desert where a beautiful forest used to be.
OK. Now let’s look at reforestation and land reclamation efforts.
Lecture 4
Architectural History (Irwin & Hexagonal House)
Listen to part of a lecture in an architectural history class.
Professor
So last week we started our unit on residential architecture in the United States. So today we’ll be surveying a number of architects who made contributions to residential architecture in the 19th century.
Now, it’s worth noting that people who designed homes at that time probably had to deal with a certain amount of discouragement. Since there were other architects who thought it was more respectable to design the kind of buildings…and maybe other structures…that were less…less utilitarian in their function. In fact, an article from an 1876 issue of a journal called The American Architect and Building News stated that, and this is a quote, they stated that “the planning of houses isn’t architecture at all”! So keep that journal article in mind as we look at the work of an architect named Harriet Morrison Irwin. Harriet Morrison Irwin was from the South, born in North Carolina in 1828. At the time, there weren’t many architects from the southern United States. And as you might imagine, very few of them were women. So Irwin was
really a pretty exceptional case. And she wasn’t even formally trained as an architect. Her educational background was in literature.
Yes, Vicky?
Student
So she just had like…unnatural gift for architecture?
Professor
Yes. She was actually a writer for several years. But she did have a penchant for math and engineering, so she read a lot about it on her own. Um…especially the architectural essays written by the British critic –John Ruskin. And John Ruskin believed what?
Student
Um…that buildings should have a lot of access to the outdoors, to nature. Ruskin said that being close to nature was great for people’s mental and physical health. Professor
Right! So that was an influence. Now, Harriet Irwin’s contribution to architecture was relatively minor but still quite interesting and unique. She designed a house with a hexagonal shape. Josh?
Student
A house with six sides? Instead of the standard, you know, four-sided home? Professor
Yeah. The rooms inside the house were also hexagonal, six-sided. So one important thing was that the rooms were arranged around a chimney in the center of the house, which could provide heat for the whole house through flues, uh, small air passageways into each room, as opposed to having a fireplace in every room, which would require more cleaning and make the air inside the house dirtier.
The house’s shape also allowed for more windows. Each room had a large wall that could fit a couple of big winters, giving every room a nice view of the outdoors. Student
Plus there would be good airflow through the house.
Professor
Yes. In warm weather when you can open all the windows. Good.
The doors to the house as well…uh…the house didn’t have a main entrance or any hallways. So there could be a couple of entry doors in different places, which like the windows, provided ready access to the outdoors.
So, what other advantages might there be to hexagonal rooms?
(Pause…no response)
OK. Think about cleaning. What part of a room is usually the hardest to clean? Like…to sweep with a broom.
Student
Oh! The corners. Because in square or rectangular rooms, the corners are at 90 degree angles. It’s hard to reach all the dust that gathers in the corners. But if Irwin’s rooms were closer to a circle than a square, it would be easier to reach all the dust and dirt with a broom. Right?
Professor
Exactly. Now, um…biographers who wrote about Irwin in the 19th century, I feel, sort of downplayed the ingenuity of her design. But I think if she had designed this house today, the same biographers would praise her for coming up with a floor plan that emphasized function, efficient function of a house, as well as a design that’s creative and unique.
In any cases, three houses were built in Irwin’s time that used her hexagonal design. And in 1869, when she was 41, Irwin became the first woman in the United States to receive a patent for an architectural design. And that speaks volumes if you ask me.