托福TPO听力24完整文本

TPO 24
Conversation 1
Narrator
Listen to a conversation between a student and a clerk in the bookstore.
Student
Hi. Can you tell me where to find New Kind of Science? By, uh, by Stephen Wolfram.
Clerk
OK!
Student
...uh, I couldn't find it.
Clerk
OK. Let me look it up on the computer for you. Who would you say the author was?
Student
It's a Stephen Wolfram.
Clerk
OK. Let's see... Hmm... no, it's not coming up. Hmm..,. I am not seeing it.
Student
Um...hmm.
Clerk
This is for a course here at the university, right?
Student
Yeah, It's assigned reading for a class I am taking.
Clerk
It's for the semester, right? You are not buying it in advance for next year or anything.
Student
No, no. It's for a class I am taking now.
Clerk
Hmm...
Student
Oh, oh, you know what? Um, it's for a graduate class. Would that maybe make a difference? I mean, I am an undergrad, but I am just taking this one class in the graduate department, so...
Clerk
No, no. I don't think that's it. That shouldn't make any difference. But, hmm... let me see... maybe it's just...it could be that whoever that entered it misspelled the title or the author's name, so I can't find it on the computer and I can't tell if it's sold out. But if it's sold out, we would probably be getting a new shipment within about a week or so.
Student
Well, uh, I was hoping to get it sooner because like we already have assignments and you know, I mean, I guess I can get it from the library.
Clerk
Right, of course. But I am trying to check. If we've ordered more, then that back orders information should be in the computer too. Let's see... back order... Wolfram, Stephen..,. no, no. I am not seeing it. I am sorry. We just don't seem to carry it.
Student
Uh-huh.
Clerk
This is odd though. What is...what's your professor's name? I could try searching for his or her classes in the database. That might help.
Student
Um...OK. It's professor Kayne.
Clerk
K-A-N-E?
Student
No. It's professor Kayne, K-A-Y-N-E. He's in the computer science department.
Clerk
Oh. It's for a computer science course, is it?
Student
Yeah.
Clerk
Well, that must be it. Computer science books are sold across the street in the computer bookstore.
Student
Are there signs up anywhere?
Clerk
I don't know.
Student
Maybe they should put some up. It could have save us both some time.
Clerk
Yeah. Well, anyway, I'll bet that's the problem. Check across the street. I’ll bet they have it. But if not, come back, and I'll help you find it somewhere else. I can call around to see if other bookstores might have it. OK?
Student
OK. Thanks a lot. Bye!
Clerk
Bye!
【Lecture 1】
Biology (Crocodile Vocalization)
Narrator: Listen to part of a lecture in a Biology class.
Professor: OK. For today, let's look at a reptile, a predator that hasn't evolved much in the last seventy million years. No discussion of reptiles would be complete without some mention of crocodiles.
Now, we tend to think of crocodiles as, uh, kind of solitary, hiding out in a swamp, uh, kind of mysterious creatures. But we are finding out that they aren't as isolated as they seem. In fact, crocodiles interact with each other in a variety of ways. One way is with vocalizations, you know, sounds generated by the animal. This is true of the whole crocodile family, which includes crocodiles themselves, alligators, etc.
Take American alligators. If you were to go to a swamp during the breeding season, you'd hear a chorus of sounds, deep grunts, hisses, these are sounds that male alligators make.
And some of them are powerful enough to make the water vibrate. This sends a strong, go-away message to the other males. So the alligator can focus on sending other sound waves through the water, sound waves that you and I couldn't even hear since they are at such low frequency. But they do reach the female alligator, who then goes to find and mate with the male.
Vocalization is um...well, it is used for other reasons, like getting attention or just, um... letting others know you are distressed. Let's see. New-born crocodiles, or hatchlings and their interactions with their mothers. When they are born, croc... baby crocodiles have a sort of muffled cry while they are in their nest. Hatchlings are really vulnerable, especially to birds and small mammals when they are born. But their mother, who has been keeping vigil nearby, hears their cry for help and carries them to safety, meaning, to water.
So she takes them out of the nest. Uh, uh, all the eggs hatched at once, so she has about forty newborns to look after. Well, she takes about fifteen out of the nest at a time, carrying them in her mouth to the nearby water. While she is taking one load of hatchlings, the others wait for her to come back.
But do you think they are quiet about it? No way. They are clamoring for the mother's attention, sort of squeaking and practically saying-don't forget about me!
I heard some great examples of this on the television program on crocodiles last week. Anyone catched it? It had a few interesting bits. But you know, uh, you have to be careful, think critically. Sometimes I don't know where these shows find their experts.
Student: Excuse me. But, um... does all that crying defeat the purpose? I mean, doesn't it attract more predators?
Professor: Hmm...good question. I guess, well, I am guessing that once the babies have the mother's attention, they are safe. She's never too far away, and, and I think...I mean, would you mess with a mother crocodile?
So after the mother transports all the youngsters, they still call to each other, and to their mother. This communication continues right through to adulthood. Crocodiles have about eighteen different sounds that they can make.
There's...um...um… you have deep grunting sounds, hisses, growls, are many different sounds to interact or send messages. This is more typical of mammals than of reptiles. I mean, crocodiles' brains are the most developed of any reptile. In that sense, they are closer to mammals' brains than other reptiles' brains. And we know that mammals, dogs for example, dogs vocalize many different sounds. Crocodiles have a similar level of, uh, vocal sophistication, if you will, which makes them unique among reptiles.
Another thing would be, um, if a hatchling gets separated from the rest of its family, once the others get far enough away, its survival instinct kicks in. It will make a loud distress call, which its siblings answer. It calls again. And they continue calling back and forth until they all find each other again.
Another thing, something that wasn't on that TV show I mentioned. Um... mother crocodiles lead their young from one area to another, like when they have to find a different source of water. Usually she will lead them at night, when it is safer for them, moving ahead and then letting out calls of reassurance so that they will follow her. Her voice helps give the babies the courage they need to leave the area and go some place that's a more desirable home for them.
【Lecture 2】
Art History (Modern Dance)
Narrator: Listen to part of a lecture in a dance history class.
Professor: As we have been studying, ballet, the classical ballet, is based on formalized movements, specific positioning of the arms, feet and the body. So, now let's move on to modern dance, also known as theatrical dance. Modern dance evolved in the late nineteenth, early twentieth century, and in most cases, audiences were very receptive to this radical new type of performing art.
Student: Um... what made modern dance so radical?
Professor: Well, for example, I think the best analogy to modern dance is modern art or modern music. Compared to their classical predecessors, these newer art forms are freer, more experimental, more improvisational.
Modern dance seeks to show how deep emotions and the music itself, how these intangible attributes can affect and inspire physical movement, and how movement can convey emotions to the audience. As I said, in classical ballet, emotions are conveyed through a set of strictly formalized movements.
Now, a pioneer of modern dance was Isadora Duncan, who was born in 1878. Isadora Duncan did study ballet briefly as a child, but she quickly developed her own unique style, which she called free dance. And by age fourteen, she was teaching her free dance to young children and giving recitals.
Her early dance technique was loosely based on the natural movements of children, running, skipping, acting out stories, also on motions from nature, waves crashing onto shore, trees swaying in the wind. Her expressive gestures were motivated from within rather than from being dictated by strict technique. Duncan also wore her hair down, ballerinas typically wear their hair in a tight bun behind the head. And instead of the short steep skirts and rigid toeshoes worn by ballerinas, Duncan wore loose, flowing tunics, and she dance bare foot. Now, that was something her audiences had never seen before.
Duncan performed in Paris composers, but avoiding set audiences, for the most part, and other European cities, dancing to the music of classical movements and steps, no two performances were alike. And adored her.
In 1904, she opened a school of modern dance in Berlin. And the next year she performed in Russia. But the Russian critics were not really kind. Some said Duncan's art form was closer to pantomime than to dance. But her style was a clear rebellion against ballet, and ballet is extremely important in Russia. A question, Julie?
Student: Yeah. What did Duncan have against ballet? I mean, she studied it as a child.
Professor: As a youngster, she might have found it too restrictive, uh, not creative enough. I think that feeling is exemplied by something that happened earlier in her career, in Russia. Duncan attended a ballet, and the lead dancer was the renowned Russian ballerina，Ana Pavlova. The following day, Pavlova invited Duncan to watch her practice.
Duncan accepted but was appalled by what she saw. To her, the exercises that Pavlova and the other ballerinas were doing seemed painful, even harmful, standing on tiptoe for hours, moving their bodies in unnatural ways. After seeing this, Duncan publically denounced ballet as a form of acrobatics, uh, complicated and excruciating mechanism she called it. This critic generated I think some undue rivalry between ballet and modern dance, and it would take a long time, many years in fact, for the rivalry to calm down.
Conversation 2
Narrator
Listen to a conversation between a student and his geography professor.
Student
Hi. Professor Brown.
Professor
Hi. Paul. What can I do for you?
Student
I have a question about the final exam. I mean, will it cover everything we've done all term? Or just what we've been doing since the mid-term exam.
Professor
Everything we've done all term.
Student
Oh, boy. You know, I am still not too clear about the hydrologic cycle, um, the transfer of water back and forth between the earth and the atmosphere. I really blew the question about it on the mid-term exam. I want to do better on the final exam. But I am still having trouble with it.
Professor
Well, uh, have you been to the tutoring center?
Student
No, not for geography anyway. Isn't that just for when you need help with writing, like an essay or a research paper.
Professor
Oh, no. you can get tutoring in a lot of subjects. Some graduate students from this department tutor there.
Student
That's good to know. But I hardly go there because I have a part-time job. I never seem to be free when they are open.
Professor
Well, they will be extending their hours when final exams begin. You might try then. But um... Well, since you are here now, can I help you with something?
Student
Well, the hydrologic cycle. I remember we went over a diagram in class. And from what I remember, water changes back and forth from water in lakes and oceans to vapor, and then back to water again when it falls as rain or snow, as precipitation. It's constantly being recycled through evaporation and condensation.
Professor
That's it. Basically. Um... so exactly what is it you don't understand?
Student
OK. I guess what I am really confused about is how the topography of the land, the mountains and valleys and stuff, affects precipitation.
Professor
OK. Good question. Precipitation is influenced by topography among other things. Um, why don't we talk about lake-effect snow? It's a phenomenon that occurs anywhere you have a large lake that doesn't freeze and have cold air flowing over it, mostly in the Northern Hemisphere.
Student
Like the great lakes in the United States?
Professor
Yeah. What happens is that the cold arctic air blows across the lake from the north in winter. And as the air crosses the lake, the lower layer is warmed by the lake water, which is much warmer than the arctic air. And as this air is warmed and picks up moisture, it becomes lighter than the air above it.
Student
So it starts to rise, right?
Professor
Yes. And clouds begin to form. When the air gets closer to the shore, it's slowed down by the land and starts to pile up. So it rises even faster because it has nowhere else to go, that's where topography comes into the picture.
Student
And then it snows because as the air rises, it cools off and loses its capacity to hold water vapor.
Professor
That's right.
Student
OK. Thanks. Any chance you'll have this question on the final?
Professor
I don't know yet. But you seem to have a handle on it.
【Lecture 3】
Archaeology (Megafauna in North America)
Narrator: Listen to part of a lecture in an archaeology class.
Professor: Between 11,000 and 10,000 B.C.E., North America was populated by a wide variety of great beasts, like mammoth and mastodons, both elephant-like creatures with big tusks, and camels, giant sloths, the list goes on. By about 10,000 B.C.E., all those giant creatures, the Megfauna of North America were gone. We don't know exactly what happened to them, but there are some theories.
One theory is that they were hunted to extinction by humans. The humans who coexisted with these giant species in North America at that time were what we today called the Clovis People. And there is a Clovis site in a valley in southern California where the remains of thirteen mammoths were found. And spear points, tools for processing meat, and fire places.
That would appear to be some pretty compelling evidences. Mammoth bones have also been found at some other Clovis sites.
But then at other Clovis sites, there's also a lot of evidence that the Clovis people mostly gather plants and hunted small game, like rabbits and wild turkeys. Also there are several places in North America where you have natural accumulations of mammoth bones that look very similar to the accumulations at the Clovis site, except there's no human debris, where the mammoth almost certainly died as a result of some kind of natural disaster. So I think it is quite likely that those thirteen mammoths in southern California also died of natural causes, and that the Clovis people simply took advantage of the situation. Um...OK. That's the hunting theory.
Now let's look at another theory, uh, an alternative to the hunting theory, the climate change theory. At around 11,500 B.C.E.，the world was coming out of an Ice Age .And with that came increased seasonality, that is, the summers became warmer, and the winters actually became colder. These extreme shifts would have put a lot of stress on the bodies of animals that were used to a more moderate range of temperatures.
But the most important impact of this increased seasonality may very well have been its effect on the distribution of plants.
Today we take for granted that there horizontal bands of plant communities. In the far north, it is tundra, which gives way to forest as you move southward. And even farther south, grasslands take over. But during the Ice Age, these plant communities actually grew together, mixed with one another. So Ice Age animals had access to many different types of plants, different types of food. But when the seasons became more distinct, the plant communities were pulled apart, that meant, in any given area, there was less plant diversity. And as a result, uh, so the theory goes, the Ice Age animals that depended on plant diversity couldn't survive. And the great beasts were the ones that needed the most diversity in their diet. Again, we have what at first seems like a pretty attractive theory, but then, how do you explain the fact that this has happened before? You know, global cooling followed by global warming, and there was no extinction then.
Uh, you know, I recently read an interesting article about an archaeologist who tried to solve this puzzle with the help of his computer. What he did was, he wrote a computer program to simulate what would happen to mammoth under certain conditions. Say, for example, there is a drought for a couple of decades, or hunters are killing or five percent of the population, and so on.
One thing he found was that humans didn't necessarily have to kill these animals in great numbers in order to nudge them toward extinction. That's because very large animals have a slow rate of reproduction, so all you have to do is remove a few young females from the herd, and you can, fairly quickly, significantly reduce the population. And then he came up with a scenario that combined some hunting by humans with some environmental stress, and...Bang! The simulated mammoths were extinct within decades.
So it seems the mixture of hunting and climate change is a likely scenario. Uh, of course, computer simulations are not a substitute for hard evidence.
【Lecture 4】
Astronomy (Shield Volcanoes on Venus)
Narrator: Listen to part of a lecture in an astronomy class.
Professor: Many people have been fascinated about Venus for centuries because of its thick cloud cover, this so-called planet of mystery and all of that. Well, what's under those clouds? What's the surface of the planet like? Some questions about the surface are still unresolved but, but we have learned a lot about it in the past several years.
First of all, let me talk about how we have been able to get past those clouds. First, there were Soviet modules that landed directly on the surface and sent back some images of what was around them. Second, we did some radar imaging from satellites from above. Radar can get through the clouds. So what have we learned? Yes, Karen?
Student: Well, I remember reading that there's not really a lot going on, that the surface of Venus is just flat and smooth in a lot of places.
Professor: Yeah, smooth in a lot of places. But that's not, um... that's not the whole picture. In other areas, you've got canyons, ripped valleys, meteo craters, uh, lava domes, these lava formations that look like giant pancakes. And also volcanoes.
Well, one of the most interesting features on the surface are in fact the shield volcanoes. Shield volcanoes formed when magma comes out of the ground in the same spot over and over again. Remember, magma is hot molten rock that's underground, and it is called lava when it reaches the surface. Uh, so the lava builds up, and hardens, and a volcano forms.
Now, the lava on Venus is thin. It spreads out easily. So shield volcanoes have very gentle sloping sides. They are called shield volcanoes, because viewed from above, they kind of resemble shields, you know, like a warrior's shield.
But what's particularly interesting about these volcanoes is that most of the volcanoes here on Earth are not shield volcanoes. Instead, they are other volcano types, like strata volcanoes, for example, which are a result of tectonic plate movement. Remember tectonic plates?
Underneath the Earth's crust, there are a number of shifting slabs or plates that are slowly moving. And in the zones on the edges of the plates where different plates meet and interact, that's where we get most of Earth's volcanoes.
On Venus, however, volcanoes are not clustered in discrete zones like they are on Earth. Instead, they are more or less randomly scattered over Venus's surface. Well, that's significant. Venus has mostly shield volcanoes, and they are randomly scattered, that indicates that Venus does not have moving tectonic plates, and that's a big difference compared to Earth. Here on Earth, moving tectonic plates are a major geological element, just crucial for the whole surface dynamic, right?
So why doesn't Venus have them? Well, there are a few theories. One of them is that this has to do with the fact that Venus has no surface water that's needed to kind of lubricate the movement of the plates, you know, like oceans on Earth. Yeah, I forgot to spell that out. Uh, Venus has no surface water.
Student: Wait a second. Did you say we have shield volcanoes on Earth? Can you give an example?
Professor: Sure. The volcanoes in the Hawaii islands, in the Pacific Ocean are shield volcanoes. They are formed over a hot spot of magma. So while on Earth we have several types of volcanoes, on Venus there's mostly the one type. Uh, Eric?
Student: Are the volcanoes on Venus still active?
Professor: Well, that's an interesting question. There is still some discussion on that point. But here's what we do now. First, the level of sulfur dioxide gas above Venus's clouds shows large and very frequent fluctuations. It is quite possible that these fluctuations, the huge increase and decrease of sulfur dioxide, happening again and again. It's quite possible that this is due to volcanic eruptions, because volcanic eruptions often emit gases. If that's the case, volcanism could very well be the root cause of Venus's thick cloud cover. And also we have observed bursts of radio energy from the planet's surface. These bursts are similar to what we see when volcanoes erupt on Earth. So this too suggests ongoing volcanic activity. But although this is intriguing evidence, no one's actually observed a Venus volcano erupting yet, so we can't be positive.