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托福TPO8閱讀真題Part2

　　Extinction of the Dinosaurs

　　Paleozoic Era 334 to 248 million years ago

　　Mesozoic Era 245 to 65 million years ago

　　-Triassic Period

　　-Jurassic Period

　　-Cretaceous Period

　　Cenozoic Era 65 million years ago to the present

　　Paleontologists have argued for a long time that the demise of the dinosaurs was caused by climatic alterations associated with slow changes in the positions of continents and seas resulting from plate tectonics. Off and on throughout the Cretaceous (the last period of the Mesozoic era, during which dinosaurs flourished), large shallow seas covered extensive areas of the continents. Data from diverse sources, including geochemical evidence preserved in seafloor sediments, indicate that the Late Cretaceous climate was milder than today's. The days were not too hot, nor the nights too cold. The summers were not too warm, nor the winters too frigid. The shallow seas on the continents probably buffered the temperature of the nearby air, keeping it relatively constant.

　　At the end of the Cretaceous, the geological record shows that these seaways retreated from the continents back into the major ocean basins. No one knows why. Over a period of about 100,000 years, while the seas pulled back, climates around the world became dramatically more extreme: warmer days, cooler nights; hotter summers, colder winters. Perhaps dinosaurs could not tolerate these extreme temperature changes and became extinct.

　　If true, though, why did cold-blooded animals such as snakes, lizards, turtles, and crocodiles survive the freezing winters and torrid summers? These animals are at the mercy of the climate to maintain a livable body temperature. It's hard to understand why they would not be affected, whereas dinosaurs were left too crippled to cope, especially if, as some scientists believe, dinosaurs were warm-blooded. Critics also point out that the shallow seaways had retreated from and advanced on the continents numerous times during the Mesozoic, so why did the dinosaurs survive the climatic changes associated with the earlier fluctuations but not with this one? Although initially appealing, the hypothesis of a simple climatic change related to sea levels is insufficient to explain all the data.

　　Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis. Many plants and animals disappear abruptly from the fossil record as one moves from layers of rock documenting the end of the Cretaceous up into rocks representing the beginning of the Cenozoic (the era after the Mesozoic). Between the last layer of Cretaceous rock and the first layer of Cenozoic rock, there is often a thin layer of clay. Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (Ir) it contained.

　　Ir has not been common at Earth's since the very beginning of the planet's history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth's core as the planet cooled and consolidated. Ir is found in high concentrations in some meteorites, in which the solar system's original chemical composition is preserved. Even today, microscopic meteorites continually bombard Earth, falling on both land and sea. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of Ir in the boundary clay. These calculations suggest that a period of about one million years would have been required. However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years. So the unusually high concentration of Ir seems to require a special explanation.

　　In view of these facts, scientists hypothesized that a single large asteroid, about 10 to 15 kilometers across, collided with Earth, and the resulting fallout created the boundary clay. Their calculations show that the impact kicked up a dust cloud that cut off sunlight for several months, inhibiting photosynthesis in plants; decreased surface temperatures on continents to below freezing; caused extreme episodes of acid rain; and significantly raised long-term global temperatures through the greenhouse effect. This disruption of food chain and climate would have eradicated the dinosaurs and other organisms in less than fifty years.

　　Paragraph 1: Paleontologists have argued for a long time that the demise of the dinosaurs was caused by climatic alterations associated with slow changes in the positions of continents and seas resulting from plate tectonics. Off and on throughout the Cretaceous (the last period of the Mesozoic era, during which dinosaurs flourished), large shallow seas covered extensive areas of the continents. Data from diverse sources, including geochemical evidence preserved in seafloor sediments, indicate that the Late Cretaceous climate was milder than today's. The days were not too hot, nor the nights too cold. The summers were not too warm, nor the winters too frigid. The shallow seas on the continents probably buffered the temperature of the nearby air, keeping it relatively constant.

　　托福TPO8閱讀題目Part2

　　1. According to paragraph 1, which of the following is true of the Late Cretaceous climate?

　　○Summers were very warm and winters were very cold.

　　○Shallow seas on the continents caused frequent temperature changes.

　　○The climate was very similar to today's climate.

　　○The climate did not change dramatically from season to season.

　　Paragraph 2: At the end of the Cretaceous, the geological record shows that these seaways retreated from the continents back into the major ocean basins. No one knows why. Over a period of about 100,000 years, while the seas pulled back, climates around the world became dramatically more extreme: warmer days, cooler nights; hotter summers, colder winters. Perhaps dinosaurs could not tolerate these extreme temperature changes and became extinct.

　　2. Which of the following reasons is suggested in paragraph 2 for the extinction of the dinosaurs?

　　○Changes in the lengths of the days and nights during the late Cretaceous period

　　○Droughts caused by the movement of seaways back into the oceans

　　○The change from mild to severe climates during the Late Cretaceous period

　　○An extreme decrease in the average yearly temperature over 10,ooo years

　　Paragraph 3: If true, though, why did cold-blooded animals such as snakes, lizards, turtles, and crocodiles survive the freezing winters and torrid summers? These animals are at the mercy of the climate to maintain a livable body temperature. It's hard to understand why they would not be affected, whereas dinosaurs were left too crippled to cope, especially if, as some scientists believe, dinosaurs were warm-blooded. Critics also point out that the shallow seaways had retreated from and advanced on the continents numerous times during the Mesozoic, so why did the dinosaurs survive the climatic changes associated with the earlier fluctuations but not with this one? Although initially appealing, the hypothesis of a simple climatic change related to sea levels is insufficient to explain all the data.

　　3. Why does the author mention the survival of "snakes, lizards, turtles, and crocodiles" in paragraph 3?

　　○To argue that dinosaurs may have become extinct because they were not cold-blooded animals

　　○To question the adequacy of the hypothesis that climatic change related to sea levels caused the extinction of the dinosaurs

　　○To present examples of animals that could maintain a livable body temperature more easily than dinosaurs

　　○To support a hypothesis that these animals were not as sensitive to climate changes in the Cretaceous period as they are today

　　4. The word "cope" in the passage is closest in meaning to

　　○ adapt

　　○ move

　　○ continue

　　○ compete

　　5. According to paragraph 3, which of the following is true of changes in climate before the Cretaceous period and the effect of these changes on dinosaurs?

　　○Climate changes associated with the movement of seaways before the Cretaceous period did not cause dinosaurs to become extinct.

　　○Changes in climate before the Cretaceous period caused severe fluctuations in sea level, resulting in the extinction of the dinosaurs.

　　○Frequent changes in climate before the Cretaceous period made dinosaurs better able to maintain a livable body temperature.

　　○B(yǎng)efore the Cretaceous period there were few changes in climate, and dinosaurs flourished.

　　6.The word "fluctuations" in the passage is closest in meaning to

　　○ extremes

　　○ retreats

　　○ periods

　　○ variations

　　Paragraph 4: Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis. Many plants and animals disappear abruptly from the fossil record as one moves from layers of rock documenting the end of the Cretaceous up into rocks representing the beginning of the Cenozoic (the era after the Mesozoic). Between the last layer of Cretaceous rock and the first layer of Cenozoic rock, there is often a thin layer of clay. Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (lr) it contained.

　　7. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? In correct choices change the meaning in important ways or leave out essential information.

　　○The fossil record suggests that there was an abrupt extinction of many plants and animals at the end of the Mesozoic era.

　　○Few fossils of the Mesozoic era have survived in the rocks that mark the end of the Cretaceous.

　　○Fossils from the Cretaceous period of the Mesozoic up to the beginning of the Cenozoic era have been removed from the layers of rock that surrounded them.

　　○Plants and animals from the Mesozoic era were unable to survive in the Cenozoic era.

　　Paragraph 4: Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis. Many plants and animals disappear abruptly from the fossil record as one moves from layers of rock documenting the end of the Cretaceous up into rocks representing the beginning of the Cenozoic (the era after the Mesozoic). Between the last layer of Cretaceous rock and the first layer of Cenozoic rock, there is often a thin layer of clay. Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (Ir) it contained.

　　8. In paragraph 4, all the following questions are answered EXCEPT:

　　○Why is there a layer of clay between the rocks of the Cretaceous and Cenozoic?

　　○Why were scientists interested in determining how long it took to deposit the layer of clay at the end of the Cretaceous?

　　○What was the effect of the surprising observation scientists made?

　　○Why did scientists want more information about the dinosaur extinctions at the end of the Cretaceous?

　　Paragraph 5: Ir has not been common at Earth's since the very beginning of the planet's history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth's core as the planet cooled and consolidated. Ir is found in high concentrations in some meteorites, in which the solar system's original chemical composition is preserved. Even today, microscopic meteorites continually bombard Earth, falling on both land and sea. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of Ir in the boundary clay. These calculations suggest that a period of about one million years would have been required. However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years. So the unusually high concentration of Ir seems to require a special explanation.

　　9. The word "bombard" in the passage is closest in meaning to

　　○ approach

　　○ strike

　　○ pass

　　○ circle

　　10. Paragraph 5 implies that a special explanation of Ir in the boundary clay is needed because

　　○the Ir in microscopic meteorites reaching Earth during the Cretaceous period would have been incorporated into Earth's core

　　○the Ir in the boundary clay was deposited much more than a million years ago

　　○the concentration of Ir in the boundary clay is higher than in microscopic meteorites

　　○the amount of Ir in the boundary clay is too great to have come from microscopic meteorites during the time the boundary clay was deposited

　　Paragraph 6: In view of these facts, scientists hypothesized that a single large asteroid, about 10 to 15 kilometers across, collided with Earth, and the resulting fallout created the boundary clay. Their calculations show that the impact kicked up a dust cloud that cut off sunlight for several months, inhibiting photosynthesis in plants; decreased surface temperatures on continents to below freezing; caused extreme episodes of acid rain; and significantly raised long-term global temperatures through the greenhouse effect. This disruption of food chain and climate would have eradicated the dinosaurs and other organisms in less than fifty years.

　　11. The word "disruption" in the passage is closest in meaning to

　　○ exhaustion

　　○ disturbance

　　○ modification

　　○ disappearance

　　12. Paragraph 6 mentions all of the following effects of the hypothesized asteroid collision EXCEPT

　　○ a large dust cloud that blocked sunlight

　　○ an immediate drop in the surface temperatures of the continents

　　○ an extreme decrease in rainfall on the continents

　　○ a long-term increase in global temperatures

　　Paragraph 5: Ir has not been common at Earth's since the very beginning of the planet's history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth's core as the planet cooled and consolidated. Ir is found in high concentrations in some meteorites, in which the solar system's original chemical composition is preserved. Even today, microscopic meteorites continually bombard Earth, falling on both land and sea. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of Ir in the boundary clay. ■ These calculations suggest that a period of about one million years would have been required. ■However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years. ■So the unusually high concentration of Ir seems to require a special explanation. ■

　　13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

　　Consequently, the idea that the Ir in the boundary clay came from microscopic meteorites cannot be accepted.

　　Where would the sentence best fit?

　　14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

　　For a long time scientists have argued that the extinction of the dinosaurs was related to climate change.

　　●

　　●

　　●

　　Answer choices

　　○A simple climate change does not explain some important data related to the extinction of the dinosaurs at the end of the Cretaceous.

　　○The retreat of the seaways at the end of the Cretaceous has not been fully explained.

　　○The abruptness of extinctions at the end of the Cretaceous and the high concentration of Ir found in clay deposited at that time have fueled the development of a new hypothesis.

　　○Extreme changes in daily and seasonal climates preceded the retreat of the seas back into the major ocean basins.

　　○Some scientists hypothesize that the extinction of the dinosaurs resulted from the effects of an asteroid collision with Earth.

　　○B(yǎng)oundary clay layers like the one between the Mesozoic and Cenozoic are used by scientists to determine the rate at which an extinct species declined

　　托福TPO8閱讀答案Part2

　　參考答案：

　　1. ○4

　　2. ○3

　　3. ○2

　　4. ○1

　　5. ○1

　　6. ○4

　　7. ○1

　　8.○1

　　9. ○2

　　10. ○4

　　11. ○2

　　12. ○3

　　13. ○3

　　14. A simple climate change

　　The abruptness of extinctions

　　Some scientists hypothesize

　　托福TPO8閱讀翻譯：Part2

　　參考翻譯：恐龍的滅絕

　　很長時間以來，古生物學(xué)家們認(rèn)為恐龍的滅亡是與因地質(zhì)構(gòu)造而引起的海洋和大陸位置變遷相關(guān)的氣候變化所致。在整個白堊紀(jì)(中生代的最后的一段時間，這時恐龍正值繁盛)，廣闊的淺海覆蓋了大量的陸地。各方面的數(shù)據(jù)，包括海床沉積中的地理化學(xué)證據(jù)，都表明白堊紀(jì)后期的氣候比現(xiàn)在的氣候要溫和得多。白天不是很熱，夜間也不是很寒冷。夏天不是太炎熱，而冬天也不是太寒冷。大陸上的淺海可能使其附近的空氣少受影響，以保持相對穩(wěn)定的溫度。

　　在白堊紀(jì)后期，地質(zhì)資料表明這些淺海都從大陸退回到主要的海洋盆地內(nèi)了，沒有人明白為什么。大約在100 000年內(nèi)，海洋收縮了，世界的氣候也隨之變得更極端：白天更熱，夜間更冷，夏天更炎熱，冬天更寒冷?？铸埢蛟S就是因為無法忍受這種嚴(yán)峻的氣溫變化因而滅絕。

　　如果真是這樣，那么為什么冷血動物，比如蛇類、蜥蜴、烏龜和鱷魚卻能夠幸免于寒冬和酷夏呢?這些動物都是依賴于氣溫以使其身體保持適合生存的溫度。很難理解它們?yōu)槭裁春敛皇苡绊?，然而恐龍卻如此的無能以至于無法適應(yīng)，尤其是有些科學(xué)家認(rèn)為恐龍是熱血動物。批評者們也指出淺海在中生代曾有過無數(shù)次的進(jìn)入大陸而又退回盆地的過程，所以為什么恐龍在前面的海洋起伏中能幸免于難，而在這一次中卻不能呢?盡管最初人們這樣認(rèn)為，但是簡單的與海平面高度有關(guān)的氣候變化假設(shè)是不足以解釋所有數(shù)據(jù)的。

　　對傳統(tǒng)的關(guān)于恐龍滅絕解釋的不滿使得人們反過來驚奇的發(fā)現(xiàn)，從而產(chǎn)生了新的假設(shè)。當(dāng)人們對比白堊紀(jì)后期的巖層資料和新生代(中生代后面的一個時期)早期的資料時發(fā)現(xiàn)很多植物和動物都突然地消失了。在白堊紀(jì)最后的一層巖石和新生代的第一層巖石之間，常有一層很薄的粘土?？茖W(xué)家們感覺到他們可以通過確定這層一厘米厚的粘土層中元素銥的含量來推測其的沉積時間，進(jìn)而推測大滅絕所用的時間。

　　自從地球以來，銥元素在地球的表面上就不常見。因為它通常是以金屬狀態(tài)存在，并隨著地球的冷卻和固結(jié)而優(yōu)先地合并到地核中了。在一些隕石中，依可能會高度富集，而這里常保存著太陽系內(nèi)原始的化學(xué)組成。直到今天，小型的隕石也在連續(xù)不斷地撞擊地球，并掉落在陸地和海洋中。通過確定在一段給定時間內(nèi)掉落在地球上的這種隕石的數(shù)量，科學(xué)家們就可以確定沉積隔層粘土的形成時間。這種計算表明形成這種沉積可能需要一百萬年。然而其他可靠的證據(jù)則表明沉積這層粘土不可能花費了一百萬年。所以這種不正常的銥的富集可能需要一種特殊的解釋。

　　考慮到這些事實，科學(xué)家們就假設(shè)有一個較大的小行星，直徑差不多有10到15公里，曾與地球相撞，所以碰撞揚起的灰塵等就形成了這層粘土層。他們的計算表明撞擊揚起的灰塵遮擋了陽光達(dá)幾個月之久，阻止了植物的光合作用，將陸地上的氣溫降到了零點之下，導(dǎo)致酸雨，通過溫室效應(yīng)造成了長期的、嚴(yán)重的全球升溫。這種對食物鏈和氣候的極大擾亂將可使恐龍和其他生物在不到50年的時間內(nèi)絕跡。

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