Extra 1
Conversation1 Narrator Listen to a conversation between a student and an employee in the campus
Conversation1
Narrator
Listen to a conversation between a student and an employee in the campus computer center.
Computer center employee
Hi, what can I help you with today?
Student
Hi, um, I wanted to—you e, the thing is, I don't know much about computers, so I was wondering if, uh, if there's a class so I can learn how to u computers, like to write papers for my class.
Computer center employee
Oh, um, we don't really offer a cour for beginners, since most students already have computing experience. But all the computers in our labs have a general tutorial installed on them. You could just go there and run it.
Student
And the tutorial explains everything? I mean, it might sound strange but I've never ud a computer.
Computer center employee
Well, all the computer labs on campus are staffed with student assistants, and I'm sure that any one of them would be more than willing to get you started.
Student
Yeah? That sounds good. But is it expensive?
Computer center employee
No, in fact, it won't cost anything; it's one of the rvices of the computer center.
Student
That's great. How do they—I mean, how do I get in touch with the student assistants? Should I just go to a computer lab and ask whoever's there?
Computer center employee
Sure, you could do that, or I can let you have a list of names of the students who are assistants in the labs. You might know one of them.
Student
什么是排比句 Actually, I think I'd prefer someone I don't know, um, so I can ask Is there anyone you'd recommend?
Computer center employee
All of our student assistants are really knowledgeable about computers. I mean, they have to be, in order to work in the It doesn't mean that they're necessarily good at but you probably won't be a beginner for very long.
Student
Hope not.
Computer center employee
And I just thought of something el. The bookstore has a lot of books on computers-there might be one for people like you, I mean, people who don't have a lot of experience with computers. I actually bought one for my father so he could learn how to u e-mail, basic word processing, that sort of thing—and it worked pretty well for him.
Student
OK, I'll try that, too. And if the bookstore doesn't have it, they can just order it for me?
Computer center employee
Right. Now is there anything el I can help you with today?
Student
Uh, just the list of names and the times they're working. I'd like to get going on this as soon as possible.
Computer center employee
Right. Good luck.
Lecture 1
Narrator
Listen to part of a lecture in an economics class.
Professor
When attempting to understand international trade, some things em so obvious that they can hardly be controverted, and other points that are important are invisible unless you've thought about the subject carefully.
Consider the following: if there's an increa in imports, let's say, um, let's say imports of furniture, and the domestic producers of furniture find this new competition very difficult and are cutting production and employment, then it ems obvious and easy to understand and many people conclude from this that increasing imports will cau generally greater unemployment at home.
What is not so obvious is that how much we import and how much tho ar
e interdependent and you can't understand the one without the other. But the exports that are generated are not easily discernable, so most people don't e them. They e only the imports of furniture rising and employment in domestic furniture production falling.
So as a result, many people argue that we ought to protect jobs by limiting imports—either by tariffs, quotas, regulations, or whatever—without realizing that this also has the effect of reducing potential future exports to the rest of the world, things that we can produce very, cost effectively and therefore profitably.
The fundamental proposition in international economics is that it makes n to import tho things that can be produced more economically abroad than at home and export things to the rest of the world that we can produce more cost effectively than produced elwhere in the world. Therefore, if we limit imports, we put ourlves in danger of not being able to export.
The details of this relationship will take much longer to explain than I can fully go into now but the point of the matter is that gains—the benefits of gains—from international trade result from being able to get things cheaper by buying them abroad than you can m
ake them at home. Now there're some things that we can make at home that we can do more economically than they can do abroad.支玉恒
In the ca of the United States, typically high-technology products, uh... are things that Americans have innovated in and started firms doing that sort of thing at which they do very well. Whereas goods that u a lot of relatively low skill labor, like furniture production, cotton production, tho are things that are frequently made more inexpensively in places where wage rates are low and the cost of using capital is very high.
However, in Florida they produce a lot of sugar, but the costs are so high, if we didn't have extensive restrictions on imports of sugar, the output of sugar would decline dramatically. But the sugar industry in the U.S. doesn't produce high-paying jobs, it us resources in ineffective ways and it blocks the import of more cost-effectively produced sugar. It, it's a very bad bargain for the people in the United States to want to protect low-paying jobs thereby halting the growth of world trading uh, more international specialization. It would be better to remove restrictions on imports and allow
other countries in countries that can produce them let them specialize in producing tho products.
Now, I agree that people who are directly affected by imports, what they is, is that their job prospects are being reduced, and their economic circumstances are getting wor. And that's a relevant problem and an important problem; what isn't so that by retraining and relocating people to places and industries where jobs are expanding rather than contracting, we can make the whole economy function more effectively and productively than by trying to block imports.
Um, what is interesting to note is that, even if there were no international trade issues, like imports, any changes that occur in a country's economy—any new technology, change in preferences, change in regulations or whatever—will lead to "adjustments" that lead some ctors of the economy to decline and others to expand.
And that's what we have to figure out, and that's a hard problem to deal with in detail, is how to facilitate people adjusting from ctors where their job prospects are not so good, and in particular where real wages aren't so high, to acquire skills that will permit them to
move into higher-paying jobs in other parts of the economy either by retraining or relocating. Helping pay for the relocation of the people would be very helpful, but trying to block the changes is really counterproductive. It makes people in our country poorer, and it makes people elwhere in the world poorer as well.
Lecture 2
Narrator
Listen to part of a lecture in a marine biology class.
Professor
I want to continue our discussion about whales. Specifically, today, um, I want to talk about whale migration—um, why whales head south for the winter. Or really why whales in the cold water of the Northern Hemisphere head south for the winter. Now, not all kinds of whales migrate, but most baleen whales do.
And interestingly enough, we still don't really know why the baleen whales migrate. We do have veral theories, however, which I'll discuss today. Uh, can anybody name one reason why baleen whales might migrate south, to the warm tropical water?
Male student
Uh, for food? You know, the whales move to warmer water in order to find a good area to feed.
Professor
Good guess. That should be an obvious reason—after all, most animals that migrate do so for the purpo of finding food. But, uh, that doesn't em to be the ca with baleen whales. To understand why, you need to know something about water temperature. There are a lot of technical reasons that I'm not going to go into right now. But let's just say that nutrients don't ri to the surface of tropical water like they do in other kinds of water. Tropical water simply never gets cold enough. So... well, what this means, uh, is that tropical water doesn't have much of the plankton that most whales feed on.
Male student
I don't understand—if there's no plankton, how do the whales survive through the winter?
Professor
Right. How do they survive? You e, they don't have to eat anything, becau they've stored up so much fat during the summer feeding ason that they can just survive off of that. So if they don't need to eat anything, we're back to our original question. Why do baleen whales migrate? Any theories? No?
Well, there's one idea out there that a lot of people believe. In fact, uh, you could say it's the most popular theory we have about whale migration. Basically, the argument is that for baleen whales, migration is a kind of balancing act. Let me explain. On one hand, whales need to take advantage of the summer months by eating as much food as they can. And that's what they can do best in the northern as. This allows them to build up a lot of fat. But in the winter, food is scarce even in the north, so what the whales need to do is save energy. And that's what migrating south can help Amanda, you have a question?
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Female student
Yes. Um, the balancing-act theory doesn't make n to me. Maybe whales might need to save energy during the winter, but wouldn't moving all the way down to tropics make them lo energy?
Professor
That's a good point, and it's one reason why this isn't a perfect theory. It does cost the whales energy to migrate, but it's easier for whales to save energy in warm water than it is to save energy in cold water, so there might still be, you know, a good reason to move south for the winter. OK?
魔法仙踪 Now, before moving on to the next chapter, I want to briefly discuss how the baleen whale manages to navigate. It's pretty remarkable, becau the whales manage to return to the same places year after year, and have to travel over an enormous area of ocean in order to do it. I mean, it's not like whales can just look at a map, right? So exactly how do they do it?
Well, a lot of experimental work still needs to be done, but we have been able to figure o
ut at least three ways the baleen whale navigates without getting lost. The first is the ability to u Earth's magnetic field like it was a map. That sounds strange, but we know that many birds u that method, u the magnetic field, and it's possible that whales have the biological ability to do the same thing.
Another theory is that if they stay clo to the coast, whales might be able to find familiar landmarks and u tho as guides. But we don't really know if a whale's eyesight is good enough to be able to do that, so that's not a perfect theory.
And finally, we know that many whales make very loud sounds that can travel literally hundreds of miles underwater. Through a process called echolocation, it's possible that the whales hear the sounds bounce off of islands or other pieces of land and u tho echoes as clues to help them find their way.
演员的歌词
Conversation 2
Narrator
Listen to a conversation between a student and a professor.
Student
Hi, uh... wondering if you had a
Professor
Of cour,
孕产期保健Student
uh, you nt me a letter recently about doing, uh, an honors project—inviting me to come in and
Professor
Right, right, well, as your academic advisor, it's my job to look out for your academic interests, and bad on your grades, and some very positive feedback I've heard from your professors, I wanted to formally invite you to consider doing an
Student
well, uh, actually I kinda wanted to quite frankly—like how much work it would probably be? I mean, I'm gonna be spending a lot of time applying to law schools next
Professor
Well, let me tell you how and then you can decide from there.
Student
OK.安全施工
Professor
Basically, the honors project is an opportunity some in-depth work on a topic you're interested in before graduating college. You register for the class, but it doesn't work the same way a regular class does—you find a professor who you want to work with—you ask the professor—a sort of mentor who's knowledgeable on the topic you're interested in—the topic you're gonna write your honors
Student
Writing a thesis? That's part of the project? Ah, like how many pages are we talking?
Professor
Usually but it's a valuable experience, writing a thesis paper.
Student
So, basically, after I register for the class, I need to ask a professor who'll sorta
Professor
Actually, you need to do that—a professor needs to agree to overe your honors project—before you register.
Student
Oh, OK...
Professor
I mean, I know it sounds kinda daunting, but that's what the professor's there for—to help guide you through the different steps of the uh... most students are very plead with they're able to demonstrate advanced rearch skills, which is important; especially in your ca, writing an honors thesis would be a
Student
You think so?
Professor
Absolutely. Especially considering your plans, since you're applying to law schools. It shows initiative, that you've done well as an undergraduate—to be allowed to do the that you're able to work independently and, of cour, you would graduate
Student
Yeah, it does sound good—it's just, you know, I've never written something like that before, so...
Professor
Well, you choo something you're interested in—maybe you can even expand a shorter rearch paper from another
Student
So, like, You know, I took this cour from Professor Connelly—his cour on
Comparative Governments last mester and, uh... did pretty well—I wrote a paper actually, on political parties in Venezuela and—and he emed to like my rearch. Anyway, he, uh, I got an A in the cour.
Professor
Good, so it sounds like you do have a general idea for a topic, and you might know what professor you want to and look, it's still a couple weeks before registration, maybe you should talk to Professor Connelly and then get back to me.
Student
Yeah, I will—thanks. I'll come by again sometime next week.
Professor
That's fine. Good luck.
Lecture 3
Narrator
Listen to part of a lecture in a journalism class. The professor has been discussing newspapers.
Professor
About 40 years ago, half of all Americans felt they'd be lost without a daily newspaper. But today, only one in ten Americans say they'd be lost without a paper. In fact, today, half of all Americans say they don't need a newspaper at all. And so people in the newspaper industry are trying to figure out how they can get more people reading the newspaper more often. They're trying to crack journalism's riddle for the ages: what makes people read newspapers? OK, well, let me ask you—as a journalism student, what do you think is the answer to this question? Elizabeth?
Female student
Um, I would probably try to improve the content of the newspaper.
Professor
Better content. Hmm. You mean like well-written editorials and articles?
Female student
Well, I mean provide more interesting content, like, I would first try to find out what readers really want and then put that into the paper.
Professor
Yes, in fact, not too long ago, there was an extensive study conducted to investigate what draws people to newspapers. Uh, they found out that there's a clear, strong link between satisfaction with content and overall readership. Tho newspapers that contained what the readers wanted most brought in the most readers. No big surpri there, right? So, what kind of content brings in readers? The study found that people-centered local news ranks at the top of stories about ordinary people. For example, you could write about the experiences of tho who were involved in a news story, and their friends The vantage points would be tho of ordinary people, not of police or OK? Now the study also showed that people want more stories about movies, TV, and weather, and fewer stories and photos about natural disasters So, to get reader satisfaction, you need to lect the right topic
s, and within tho topics, the right news events or stories to cover. Yes, James?
Male student
It ems to me that a lot of what you just mentioned doesn't line up with the principles of good journalism. Catering to readers' tastes may improve overall readership, but what about the social responsibilities that newspapers have? I mean, there are some topics that newspapers need to write about in order to rve the public interest. Tho topics may not always be fun and interesting for the average reader, but it's still the newspaper's responsibility to make that information available to the public.
Professor
That's a good point. You need a good mix of content. You can't just rush towards an attractive topic and forget about the reporting role of newspapers. There's a danger of going soft—newspapers do have to perform their obligations to citizens. So what newspapers sometimes do is to combine rious journalism with a reader-friendly prentation. Um, let me give you an example: When the justice department opened an investigation on the local police—some pretty rious stuff that could be boring to some r
eaders—well, one local newspaper ran a lead story on their front page, but they also simplified the format by including small breakout boxes that prented—in a nutshell—the highlights of the story. That way, they could report the rious stories they needed to report, and, and still hold their readers' attention. OK? Uh, going back to the rearch on readership growth we were Uh, the most vital step of all, the study shows, may be making the paper easier to u. How can we make the paper "easier to u"? Well, it means stories need to include information, such as phone numbers, times, dates, address, Web sites and the like, so that readers can "go and do" things bad on what they've read.
Female student
Professor Ellington? Um, when you said we need to make the paper "easier to u," I thought you were gonna say something about u of graphics, colors, and stuff like that.
Professor
Well, I guess tho things do help in a way, but it turned out that tho contemporary touches, uh, such as more attractive designs, extensive u of color, and informational gr
aphics matter much less than you'd expect. Surprising, isn't it?
Female student
Yeah, Um, how about rvice? Does the study say anything about improving rvice? I don't think people are gonna subscribe if the paper doesn't arrive, or shows
Professor
Or shows up wet, which by the way, happened to me this morning. Oh, absolutely. Service affects readership. In fact, improving your rvice is much more likely to increa your readership than making changes in your Not only on-time delivery in good condition, but also things like efficient billing, affordability, um... Yes?
Female student
They could also, like, increa the number of sites where they ll single copies.
Professor
Certainly that's one way to improve rvice.
心中有朵马兰花
Lecture 4
Narrator
Listen to part of a lecture in a geology class.
Professor
Um, beginning in the late 1960s, geologists began to uncover some evidence of a rather surprising kind when um... at various places around the world. What they found out when they examined rocks from the period from about 750 million years ago to about 580 million years ago, they it emed that glaciers covered the entire surface of the Earth—from pole to pole, including the tropics.
Um... how did they come to this astonishing conclusion? What was the evidence for this? Especially when glaciers today are found only at the poles ... or in the mountains.
Well, uh... basically when glaciers grow and move they leave behind a distinctive deposi
t consisting of, at least on the top level, of ground up little bits they almost look like rocks that have been deposited by streams,
if you've ever en tho. And that's caud becau, although the glacier is ice, it is actually flowing very slowly and as it moves it grinds the top layer of rock, it breaks off pieces and carries them away. So when you have glaciation you have a distinctive pattern of the pieces of rock which are called "erratics."
Erratics they're the stones that are often carried long distances by glaciers.
So, in the 1960s and onward up through the 1990s, we keep finding evidence for glaciation, no matter what even in tropical latitudes. Now, today there are glaciers in the tropics but only at very high elevations. But 750 million years ago, apparently there were glaciers even at a level in the tropics.
How could this have happened?
Well, the growth of glaciers, uh, benefits, if you will, from a kind of a positive feedback loop called the "ice-albedo effect."
With the ice-albedo effect, glaciers—'cau they're white—reflect light and
much more than does or soil and rock, which are dark and absorb heat. So, the more glaciers there are, the more heat is reflected, so the climate gets cooler, and glaciers grow even more.
normally, on a global scale, there is a major process that functions to curb the growth of glaciers. And, that process involves carbon dioxide.
Now, we're all familiar with the notion that carbon dioxide is what we call a "greenhou gas." The more carbon dioxide there is in the atmosphere, the more heat the atmosphere retains. That's what a greenhou gas does. So, the greenhou-gas effect is kinda the opposite of the albedo effect.
Um... now as when silicate rocks, which is a very common class of rock, when they're expod to the air and to normal weathering, they erode. Carbon dioxide is attracted to the eroding rocks and binds to them, forming calcium carbonate.
Calcium carbonate is eventually washed into the ocean where it ttles to the bottom. This process, this forming of calcium carbonate, has the effect of sucking the carbon dioxide out of the air and storing it at the bottom of the ocean.
Now, follow me here. The process that's sucking carbon dioxide out of the air, keeping the greenhou gas levels low, cannot happen if the rock is covered with ice.
So, while glaciers reflect light cooling the Earth, they at the same time cover rocks so there's less calcium which leaves more carbon dioxide in the atmosphere. Higher levels of carbon dioxide keep the which slows the growth of glaciers. So, it's a balance, and the glacier growth remains pretty much under control.
Now, what happened 750 million years ago to upt that balance? It ems a relatively simple
750 million all the major continents are rocky, bare, and pretty much lined up along the equator; they hadn't yet moved to where they are today. So, what happened was, perhaps a slight the very slight and temporary cooling of the Sun—which still happens from time to time—and the Earth starts to cool, the ice starts to spread on starting at the poles.
Now, by the time the ice reaches about two-thirds of the way to the equator, it's too late.
becau the continents are the last things to be covered by glaciers, they the rocks keep eroding and the carbon dioxide levels So, the ice-albedo effect from the glaciers is increasing in strength while the atmosphere continues to lo its ability to retain heat making glacier growth unstoppable. Now you have what's called a "runaway freeze." And for perhaps as long as 50 million years, possibly with some interludes, the Earth was frozen from pole to pole, like a giant snowball.
