1. What is the lecture mainly about?
A. An example of rapid climate change
B. A comparison of two mechanisms of climate change
C. The weather conditions in the present-day Sahara
D. Recent geological findings made in the Sahara
2.Not long ago, the Sahara had a different climate. What evidence does the professor mention to support this? [Click on 3 answers.]
A. Ancient pollen
B. Bones from large animals
C. Rock paintings
D. Agriculture in ancient Egypt
E. Underground water
3.In the lecture, what do the Ice Age and the creation of the Sahara Desert both illustrate about past climate changes? [Click on 2 answers.]
A. That some climate changes benefitted the development of civilization
B. That some climate changes were not caused by human activity
C. That some climate changes were caused by a decrease of moisture in the atmosphere
D. That some climate changes were caused by changes in Earth’s motion and position
4.What started the runaway effect that led to the Sahara area of north Africa becoming a desert?
A. The prevailing winds became stronger.
B. The seasonal rains moved to a different area.
C. The vegetation started to die off in large areas.
D. The soil lost its ability to retain rainwater.
5.The professor mentions a theory that people migrating from the Sahara were important to the development of the Egyptian civilization. Which sentence best describes the professor’s attitude toward this theory?
A. It is exciting because it perfectly explains recent archaeological discoveries.
B. It is problematic because it goes too far beyond the generally available data.
C. It raises an interesting possibility and he hopes to see more evidence for it.
D. It cannot be taken seriously until it explains how the migrants got to Egypt.
6.Why does the professor say this:
A. To correct a misstatement he made about the Sahara’s climate
B. To suggest that the current dryness of the Sahara is exaggerated
C. To indicate that scientists are not in agreement about the Sahara’s past climate
D. To emphasize the difference between the current and past climates of the Sahara
答案：1A 2ACE 3BD 4B 5C 6D
Listen to part of a lecture in an Earth Science class.
MALE PROFESSOR
We’re really just now beginning to understand how quickly drastic climate change can take place. We can see past occurrences of climate change that took place over just a few hundred years. Take hm the Sahara desert in Northern Africa.(題目1. What is the lecture mainly about? A. An example of rapid climate change 答案出處)
The Sahara was really different 6,000 years ago. I mean, you wouldn’t call it a tropical paradise or anything--ah or maybe you would if you think about how today in some parts of the Sahara it only rains about once a century.(題目6.Why does the professor say this: ah or maybe you would if you think about how today in some parts of the Sahara it only rains about once a century. D. To emphasize the difference between the current and past climates of the Sahara 答案出處) Hm but basically, you had greenery and you had water. And what I find particularly interesting, amazing, really what really indicates how un-desert-like the Sahara was thousands of years ago, was something painted on a rock prehistoric art –hippopotamuses. As you know, hippos need a lot of water, and hence... (題目2.Not long ago, the Sahara had a different climate. What evidence does the professor mention to support this? [Click on 3 answers.] C. Rock paintings 答案出處；此處出現了生詞hippopotamuses,如果詞彙量夠大，知道是河馬的意思能夠使聽力非常順暢；大多人遇到的問題就是，聽到河馬這個詞時反應不過來同時又因為想記下這個詞或者回憶這個詞的詞義而錯過之後的聽力內容導致漏聽，從而掌握不了文章的邏輯；應對辦法：聽力文本中的生詞有一部分是以專有名詞形式出現的，對於這些詞做筆記時可以做特殊標註，如HIPPOP,起到提示定位的作用，如果這個生詞很重要，在題幹或選項中出現時，可以根據標註找到定位)Hence what?
FEMALE STUDENT
They need to live near a large source of water year-round.
MALE PROFESSOR
That’s right.
MALE STUDENT
But how’s that proof that the Sahara used to be a lot wetter? I mean, the people who painted those hippos…well, couldn’t they have seen them on their travels?
MALE PROFESSOR
OK, in principle they could, Carl. But the rock paintings aren’t the only evidence. Beneath the Sahara are huge aquifers, basically a sea of fresh water that’s perhaps a million years old, filtered through rock layers. And, ah an-an then there’s fossilized pollen from low shrubs and grasses that once grew in the Sahara. In fact these plants still grow ah but hundreds of miles away in more vegetated areas. Anyway, it’s this
fossilized pollen, along with the aquifers, and the rock paintings—these three things are all evidence that the Sahara was once much greener than it is today, that there were hippos and probably elephants, and giraffes, and so on.(題目2.Not long ago, the Sahara had a different climate. What evidence does the professor mention to support this? [Click on 3 answers.] A. Ancient pollen C. Rock paintings E. Underground water 答案出處 注意託福聽力常見的就是對一個問題的答案反覆闡述並作總結，記錄筆記時留意重複出現的內容和總結部分的內容)MALE STUDENT
So, what happened?
MALE PROFESSOR
How did it happen? Well now we’re so used to hearing about how human activities are affecting the climate, right; but that takes the focus away from the natural variations in the Earth’s climate. Like the Ice Age, right? The planet was practically covered in ice just a few thousand years ago.(題目3.In the lecture, what do the Ice Age and the creation of the Sahara Desert both illustrate about past climate changes? [Click on 2 answers.] B. That some climate changes were not caused by human activity答案出處)
Now, as far as the Sahara goes, there’s some recent literature that points to the migration of the monsoon in that area.
FEMALE STUDENT & MALE STUDENT
“huh?”
MALE PROFESSOR
What do I mean? OK. A monsoon is a seasonal wind that can bring in a large amount of rainfall. Now, if the monsoon migrates, well that means the rains move to another area, right?(題目4.What started the runaway effect that led to the Sahara area of north Africa becoming a desert? B. The seasonal rains moved to a different area.答案出處)
So what caused the monsoon to migrate? Well, the answer is the dynamics of Earth’s motions--the same thing that caused the Ice Age, by the way.The Earth’s not always the same distance from the Sun. And it’s not always tilting toward the Sun at the same angle. There’re slight variations in these two parameters. They’re gradual variations, but their effects can be pretty abrupt, and can cause the climate to change in just a few hundred years.(題目3.In the lecture, what do the Ice Age and the creation of the Sahara Desert both illustrate about past climate changes? [Click on 2 answers.] D. That some climate changes were caused by changes in Earth’s motion and position答案出處)
FEMALE STUDENT
That’s abrupt?
MALE PROFESSOR
Well, yeah, considering that other climate shifts take thousands of years, this one’s pretty abrupt. So these changes in the planet’s motions, they caused the climate to change; but it was also compounded.What the Sahara experienced was a sort of runaway drying effect.
As I said, the monsoon migrated south—so there was less rain in the Sahara. The land started to get drier—which in turn caused a huge decrease in the amount of vegetation, because vegetation doesn’t grow as well in dry soil, right? And then, less vegetation means the soil can’t hold water as well—the soil loses its ability to retain water when it does rain. So then you have less moisture to help clouds form…nothing to evaporate for cloud formation. And then the cycle continues—less rain, drier soil, less vegetation, fewer clouds, less rain, etcetera, etcetera.(題目5.The professor mentions a theory that people migrating from the Sahara were important to the development of the Egyptian civilization. Which sentence best describes the professor’s attitude toward this theory? C. It raises an interesting possibility and he hopes to see more evidence for it.答案出處)
MALE STUDENT
But what about the people who made the rock paintings?
MALE PROFESSOR
Good question. No one really knows. But there might be some connection to ancient Egypt. At about the same time that the Sahara was becoming a desert, mm…5,000 years ago, Egypt really began to flourish out in the Nile River Valley. And that’s not that far away. So it’s only logical to hypothesize that a lot of these people migrated to the Nile Valley when they realized that this was more than a temporary drought. And some people take this a step further--and that’s ok, that’s science--and they hypothesize that this migration actually provided an important impetus in the development of ancient Egypt.
Well, we’ll stay tuned on that.
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