Narrator

Listen to part of a lecture in a geology class.

Professor

Ok, let's get started. Great. Today I want to talk about a way in which we are able to determine how old a piece of land, or some other geologic feature is - dating techniques. I'm going to talk about a particular dating technique. Why? Good dating is a key to good analysis. In other words, if you want to know how a land formation was formed, the first thing you probably want to know is how old it is. It's fundamental.

Um… Take the Grand Canyon for instance. Now, we geologists thought we had a pretty good idea of how the Grand Canyon in the southwestern United States was formed. We knew that it was formed from sandstone that solidified somewhere between 150 and 300 million years ago. Before it solidified, it was just regular sand. Essentially it was part of a vast desert. And until just recently, most of us thought the sand had come from an ancient mountain range fairly close by that flattened out over time. That's been the conventional wisdom among geologists for quite some time. But now we've learned something different, and quite surprising, using a technique called Uranium-Lead Dating.

I should say that Uranium-Lead Dating has been around for quite a while. But there have been some recent refinements. I will get into this in a minute. Anyway, Uranium-Lead Dating has produced some surprises. Two geologists discovered that about half of the sand from the Grand Canyon was actually once part of the Appalachian Mountains. That's really eye-opening news, since the Appalachian Mountain Range is, of course, thousands of kilometers to the east of the Grand Canyon. Sounds pretty unbelievable, right?

Of course, the obvious question is how did that sand end up so far west? The theory is that huge rivers and wind carried the sand west where it mixed in with the sand that was already there. Well, this was a pretty revolutionary finding. Um… and it was basically because of Uranium-Lead Dating. Why? Well, as everyone in this class should know, we usually look at the grain type within sandstone, meaning the actual particles in the sandstone, to determine where it came from. You can do other things too, like look at the wind or water that brought the grains to their location and figure out which way it was flowing. But that's only useful up to a point, and that's not what these two geologists did.

Uranium-Lead Dating allowed them to go about it in an entirely different way. What they did was: they looked at the grains of Zircon in the sandstone. Zircon is a material that contains radioactive Uranium, which makes it very useful for dating purposes. Zircon starts off as molten magma, the hot lava from volcanoes. This magma then crystallizes. And when Zircon crystallizes, the Uranium inside it begins to change into Lead. So if you measure the amount of Lead in the Zircon grain, you can figure out when the grain was formed. After that, you can determine the age of Zircon from different mountain ranges. Once you do that, you can compare the age of the Zircon in the sandstone in your sample to the age of the Zircon in the mountains. If the age of the Zircon matches the age of one of the mountain ranges, then it means the sandstone actually used to be part of that particular mountain range. Is everybody with me on that? Good.

So, in this case, Uranium-Lead Dating was used to establish that half of the sandstone in the samples was formed at the same time the granite in the Appalachian Mountains was formed. So because of this, this new way of doing Uranium-Lead Dating, we've been able to determine that one of our major assumptions about the Grand Canyon was wrong.

Like I said before, Uranium-Lead Dating has been with us for a while. But, um… until recently, in order to do it, you really had to study many individual grains. And it took a long time before you got results. It just wasn't very efficient. And it wasn't very accurate. But technical advances have cut down on the number of grains you have to study, so you get your results faster. So I'll predict that Uranium-Lead Dating is going to become an increasingly popular dating method.

There are a few pretty exciting possibilities for Uranium-Lead Dating. Here is one that comes to mind. You know the theory that earth's continents were once joined together and only split apart relatively recently? Well, with Uranium-Lead Dating, we could prove that more conclusively. If they show evidence of once having been joined, that could really tell us a lot about the early history of the planet's geology.

Conversation 2

1. What is the conversation mainly about?

l A lesson Mathew prepared for his students

l A class Mathew has been observing

l A term paper that Mathew has written

l A problem in Mathew's classroom

2. What is Mathew's opinion about observing Mr. Grable's third-grade class?

l It will help him become a more effective teacher

l It could help improve his study habits

l It has improved his public-speaking skills

l It may be the most difficult assignment he has had

3. Why does Mathew mention Greek and Roman mythology?

l To identify a topic frequently discussed in third grade

l To get the professor's opinion about a lesson he taught

l To make a suggestion to improve the class he is taking

l To illustrate a technique used to teach a third-grade class

4. What important skills did Mr. Grable introduce to his third-grade class?

Click on 3 answers

l Reviewing other student's reports

l Using books in the library

l Interviewing their classmates

l Speaking in public

l Writing reports

5. What will Mathew probably do in next Wednesday's class?

l Hand in his assignment early

l Try to start a study group

l Make a presentation to the class

l Choose a topic for his paper

Narrator

Listen to part of a conversation between a student and his professor.

Professor

Hi Mathew, I'm glad you can come in today. You've been observing Mr. Grable's third-grade class for your approaches to education paper, right?

Student

Hmmm, yes. I go over the Johnson Elementary School, you know, to watch Mr. Grable teach the children in class. It's been amazing, I mean, I'm just learning so much from just watching him. I'm so glad the classroom observations are a requirement for the education program. I mean it's like the best thing ever to prepare you to be a good teacher.

Professor

Well, I'm glad to see you feel that way, Mathew. You know, that's the goal. So, I've been reading over your observation notes and I'm quite interested in what's going on, in particular what's the astronomy unit he's been teaching.

Student

The astronomy unit?

Professor

It seems that Mr. Grable has mastered the interdisciplinary approach to teaching — the way we've been talking about in class.

Student

Oh! OK, yeah, so like when he was teaching them astronomy, he didn't just teach them the names of the planets, he used it as a way to teach mythology.

Professor

Really! So, how did he do that?

Student

Well, some of the students could already name the planets, but they didn't know that the names had any meaning — the stories behind them.

Professor

So, he…

Student

He introduced Greek and Roman mythology as a way of explaining. Like, you know, how like Jupiter's the biggest planet, right, and how Jupiter was the name of the king of the gods in Roman mythology, right? So since Jupiter, the planet, is the largest planet in our solar system, it's like the king of the planets, like Jupiter was the king of all the gods.

Professor

Oh, Mathew, that's a great example.

Student

Yeah! And each student chose a planet and then did research on it to write a report and make a presentation. They went to the library to do the research, then they made presentations about the planet they chose.

Professor

So, in one science unit, in which the focus was astronomy, the students also learned about the literature of Greek and Roman mythology, used research skills in the library, wrote a report and practiced their oral presentation skills.

Student

Exactly! He used this one topic to teach third-grades all that stuff — how to use the books in the library, to write reports, and even how to speak in public. Plus they had a great time doing it.

Professor

You know, Mathew, this is just what we've been talking about in our class. I'm sure everyone can learn something from your experience. You know, Mathew, I'd love for you to talk about this astronomy unit in class on Wednesday.

Student

Really?! Hmmm… ‘cause I don't really think I'll have any time to write my paper by then.

Professor

Oh, you won't need to write anything new just yet. For Wednesday, use your class observation notes and explain the things we've discussed today.

Student

Ok, that sounds all right.

Lecture 3

1. What is the lecture mainly about?

l Art in the Neolithic period

l The site of a Neolithic town

l Methods of making stone tools

l The domestication of plants and animals by early farmers

7. What does the professor imply about the tools used by the people of Catalhoyuk?

l They were made of stone that came from Catalhoyuk

l They were among the sharpest tools available at the time

l They were often used in religious rituals

l They were used primarily for agriculture

8. What does the professor say about the entrances to the houses in Catalhoyuk?

Click on 2 answers

l They were in the roof

l They were usually kept closed

l They allowed smoke to escape from the house

l They stood opposite one another across narrow streets

9. What does the professor say about Catalhoyuk graves?

l The graves contained precious stones

l Many people were buried in each grave

l The grave were located under the house floors

l The graves contained ashes rather than bones

10. What does the professor think of the idea that the inhabitants of Catalhoyuk deliberately arranged their house so that they could live near their ancestors' graves?

l She thinks it is a good guess, but only a guess

l She thinks some evidence supports it, but other evidence contradicts it

l She thinks that further excavations will soon disprove it

l She thinks that it is not appropriate to make such guesses about the distant past

11. What are three things the professor says about the artwork of Catalhoyuk?

Click on 3 answers

l It was clearly important to the Catalhoyuk religion

l It became covered with soot

l It often shows farmers at work

l Its significance is unknown

l It contains many hunting scenes

Narrator

Listen to part of a lecture in an archaeology class.

Professor

OK, we've been talking about early agriculture in the near east. So let's concentrate on one site and see what we can learn from it. Let's look at Catalhoyuk. Ah… I'd better write that down. Catalhoyuk, that's about as close as we get in English. It's Turkish, really. The sites in modern day Turkey, and who knows what the original inhabitants called it. Anyway, uh…Catalhoyuk wasn't the first agricultural settlement in the near east, but it was pretty early, settled about 9000 years ago in the Neolithic period. And ... umm... the settlement...ah...town really, lasted about a thousand years and grew to a size of about eight or ten thousand people. That certainly makes it one of the largest towns in the world at that time.

One of the things that make the settlement of this size impressive is the time period. It's the Neolithic, remember, the late Stone Age. So the people that lived there had only stone tools, no metals. So everything they accomplished, like building this town, they did with just stone, plus wood, bricks, that sort of thing. But you got to remember that it wasn't just any stone they had, they had obsidian. And umm... obsidian is a black, volcanic, well, almost like glass. It flakes very nicely into really sharp points. The sharpest tools of the entire Stone Age were made of obsidian. And urrr... the people of Catalhoyuk got theirs from further inland, from central Turkey, traded for it, probably.

Anyway, what I wanna focus on is the way the town was built. The houses are all rectangular, one story made of sun dried bricks. But what's really interesting is that there are no spaces between them, no streets in other words, and so generally no doors on the houses either. People walked around on the roofs and entered the house through a hatchway on the roof, down a wooden ladder. You can still see the diagonal marks of the ladders in the plaster on the inside walls. Once you were in the house, there would be one main room and a couple of small rooms for storage. The main room had the hearths, for cooking and for heat. It would've been pretty cold during the winters. And it also looks like they made their tools near the fire. There tends to be a lot of obsidian flakes and chips in the hearth ashes, but no chimney. The smoke just went out the same hatchway that people used for going in and out themselves. So there would have been an open fire inside the house with only one hole in the roof to let the smoke out. You and I would have found it a bit too smoky in there. You can see on the walls, which they plastered and decorated with paintings. They ended up with a layer of black soot on them, and so did people's lungs. The bones found in the graves show a layer of soot on the inside of the ribs.

And that's another unusual feature of Catalhoyuk, the burial sites. The graves have all been found under the houses, right under the floors. And it maybe this burial custom that explains why the houses were packed in so tightly without streets. I mean, you might think it was for protection or something, but there has been no evidence found yet of any violent attack that would indicate that kind of danger. It maybe they wanted to live as near as possible to their ancestors' graves and be buried near them themselves. But it makes a good point.

Based on excavations, we can know the layout of the houses and the location of the graves, but we're only guessing when we tried to say why they did it that way. That's the way it is with archaeology. You are dealing with the physical remains that people left behind. We have no sure access to what they thought and how they felt about things. I mean it's interesting to speculate.

And the physical artifacts can give us clues, but there is a lot we can't really know. So, for instance, their art. They painted on the plastered walls and usually they painted hunting scenes with wild animals in them. Now they did hunt and they also raised cereal crops and kept sheep, but we don't know why so many of the paintings are of hunting scenes. Was it supposed to have religious or magical significance? That's the kind of thing we can only guess at based on clues. And hopefully, further excavation of Catalhoyuk will yield more clues. But we'll probably never know for sure.

Lecture 4

12. What is the main topic of the lecture?

l The types of habitats marmots prefer

l Methods of observing marmot behavior

l Feeding habits of some marmot species

l Differences in behavior between marmot species

13. According to the case study, why are marmots ideal for observation?

l They do not hide from humans

l They reside in many regions throughout North America

l They are active in open areas during the day

l Their burrows are easy to locate

14. Drag the appropriate description of each marmot species' behavior to the box below the marmot's name.

Click on a phrase, then drag it to the space where it belongs.

One of the phrases will not be used

Displays aggressive tendencies is family oriented says active during the winter

Olympic Marmot Eastern Marmot

15. What reason does the professor give for the difference in marmot behavior patterns?

l Type of food available

l The size of the population

l Interaction with other marmot species

l Adaptations to the climate

16. Why does the professor say this?

l To inform the student that his definition is incorrect

l To suggest that the student did not do the reading

l To encourage the student to try again

l To change the topic of discussion

17. Why does the professor say this?

l To express a similar concern

l To encourage the student to explain what she means

l To address the student's concern

l To agree with the student

Narrator

Listen to part of a lecture in a biology class.

Professor

For today's discussion, we'll review the case study on how some animals have behaviorally adapted to their environments. Now you had to read about two animal species, the Eastern marmot and the Olympic marmot. Marmots are rodents. They are large ground squirrels, about the size of an average house cat. And they live in a variety of habitats. And even though they spend the significant portion of the year hibernating, according to this case study, marmots are still considered excellent subjects for animal behavioral studies. Why is that?

Student

Well, when they are not hibernating, you can find them in open areas. And they are pretty active during the day, which makes them easy to observe, right?

Professor

Uh-ha, so first let's discuss the Eastern marmots. They reside throughout the eastern region of North America where there is a temperate climate, where the growing season lasts for at least five months of the year, which is when they do all their mating, playing and eating.

Student

Oh, I see. At first I wasn't sure what growing season meant, just from the reading. But now I get it. It's the amount of time it takes for them to grow, right? So it would be five months?

Professor

Umm? Oh, uh… I'm sorry but no. It has nothing to do with that. It's not about the time it takes for Eastern marmots to grow. It's when the food is available. That is when it's not covered in snow and there is no frost covering the grass and, umm, vegetative parts of a plant's herbs and the flowers the marmots like to eat. So growing season refers to the availability of the food they eat, OK? So now how would you describe the Eastern marmots' social habits?

Student

Well, they are really territorial, and loners, and just so aggressive even with other Eastern marmots. And their mating ritual is just so impersonal.

Professor

Uh-ha? Now when they emerge in the spring from hibernation, the mating process begins. For them, well, they come together to mate and then they go their separate ways. Then about six to eight weeks after birth, the offspring leave their mothers.

Student

Really? Just six weeks? Is that possible for the offspring to make it on their own so young?

Professor

Well, it's not as if they aren't ready for the real world because they are. Remember, they mature quickly and the weather's nice. Also they live in open fields where there is lots of edible vegetation. So roughly six weeks after birth, Eastern marmots are just old enough to take their chances of surviving in the temperate environment. So how does this relate to their behavior?

Student

Oh, I get it. Since the climate's not too bad, the Eastern marmots don't have to rely on each other too much and they really don't need to stay together as a family to survive either.

Professor

Uh-ha. Any contrast, the Olympic marmots? What about them?

Student

Well, they live together as a family and take care of their young until they are at least two years old. They're really friendly with each other. And what I really like is that they even have greeting ceremonies. And they are not at all aggressive and territorial like the Eastern marmots. So their social behavior is so different from Eastern marmots because of the climate where they live? That seems so bizarre.

Professor

Well, the Olympic marmots inhabit meadows high in the Olympic Mountains where the weather conditions are much harsher. So there is a lot more wind and snow. The growing season only lasts about two to three months. So in that much shorter period of time, all the Olympic marmots, male and female, eat, play, work and nurture the young together. Because the climate is so harsh, cooperation increases the survival rate of the Olympic marmots. They keep their young at home until they are physically able to survive on their own. This could explain why the social behavior of the Olympic marmots is so unlike that of the Eastern marmots.

参考答案：

Section 2

1.B 2.A 3.D 4.BDE 5.C 6.B 7.B 8.AC 9.C 10.A 11.BDE 12.D 13.C 14.A② B① 15.D 16.A 17.C