Permian Extinction托福聽力原文翻譯及問題答案

Permian Extinction托福聽力原文翻譯及問題答案

一、Permian Extinction托福聽力原文：

Narrator:Listen to part of a lecture in an Earth science class.

MALE PROFESSOR:Let's review something from last week.We talked about an event that happened 65 million years ago.Anyone?FEMALE STUDENT:An asteroid hit Earth.Um...well,we think an asteroid hit Earth,near the Yucatan Peninsula,in Mexico,and that wiped out all the dinosaurs.MALE PROFESSOR:Right.I wouldn't say that we've got 100%proof,but there's very strong evidence that this is why that mass extinction occurred.Okay.But did you know there was an earlier extinction far greater than the one that killed off the dinosaurs?It was what we call the Permian Extinction.Now,way back about 290 million years ago,at the beginning of the Permian Period,there was just one big continent,a super continent.And as the climate warmed up,plant and animal species began to diversify profusely.So life during the Permian Period was abundant and diverse.But about 250 million years ago,the Permian Period ended with a rapid mass extinction,something happened that wiped out 75%of the land animals and over 95%of ocean life.So what was it?What could have caused this.Well,with the all the evidence that it was an asteroid that led to the dinosaur extinction,we began asking ourselves:is it possible that another asteroid much earlier caused the Permian Extinction?And so researchers have been looking for an impact crater.FEMALE STUDENT:I thought the Permian Extinction was caused by a decline in sea water oxygen levels.Isn't that what's in the textbook?MALE PROFESSOR:But don't forget the textbook makes it very clear that's only a theory.FEMALE STUDENT:And it mentions something about volcanic eruptions too.MALE PROFESSOR:It does,but now this new theory has led to a search for evidence of an asteroid impact.And one place of interest is a region called Wilkes Land in eastern Antarctica.A few years ago,a researcher reported a strange anomaly beneath the ice in Wilkes Land.Evidence of what may be a mascon.That's just short for mass concentration.When an asteroid hits Earth,when it slams into Earth's crust,we think that causes molten rock from deep below the surface to rise up into the impact area.Sort of like if you bump your head,you get a big lump under the skin.Fluid makes the area swell.Anyway,the material flowing up from below the crust is more dense than the crust itself.So that's how we get a mascon,a spot in the crust with newer crust material that's more dense than the material all around it.There're lots of mascons on the moon too,where a mascon's density causes a small increase in the local gravity that can be measured and mapped by orbiting spacecraft.And where do these mascons tend to be found?In the centers of impact craters on the moon's surface.But back to Wilkes Land.We're not certain that the mascon there...what might be a mascon...was actually caused by the impact of an asteroid,but there does seem to be evidence.Researchers notice a gravity anomaly similar to those on the moon.And the spot where the gravity readings are especially high...this is right in the middle of a 500-kilometer wide,circular ridge,what could be part of an old impact crater.And if there was an asteroid impact there in Wilkes Land,the next question is:did it happen 250 million years ago?Because that would put it when in geologic history?

FEMALE STUDENT:At the end of the Permian Period?Right when those animals went extinct.MALE PROFESSOR:Exactly.

FEMALE STUDENT:But can't researchers figure that out by studying the rocks there in Wilkes Land...where this impact supposedly took place?MALE PROFESSOR:Well,to get to anything from that long ago,we would have to drill down to about a mile,about 1.6 kilometers of solid ice that covers the area today.And that's not likely to happen.But speaking of rocks,I should mention that Wilkes Land is not the only place of interest here.There's another called the Bedout High off the coast of Australia.And we have rock samples from the Bedout High.Some apparently have extraterrestrial origin.I mean,they show the effects of extreme temperatures and pressures,the level of extremes produced only by an impact.And as for their age,well,they do in fact,date back to about 250 million years ago.

二、Permian Extinction托福聽力中文翻譯：

旁白：聽地球科學(xué)課上的一部分講座。

男教授：讓我們復(fù)習(xí)一下上周的內(nèi)容。我們討論了6500萬年前發(fā)生的一件事。任何人女學(xué)生：小行星撞擊地球。嗯…嗯，我們認(rèn)為一顆小行星撞擊了地球，在墨西哥尤卡坦半島附近，并消滅了所有的恐龍。男教授：對。我不會說我們有100%的證據(jù)，但有非常有力的證據(jù)表明，這就是大滅絕發(fā)生的原因?？梢缘悄阒绬?，有一次比殺死恐龍的那次更為早期的滅絕？這就是我們所說的二疊紀(jì)滅絕?，F(xiàn)在，回到大約2.9億年前，在二疊紀(jì)初期，只有一個大大陸，一個超級大陸。隨著氣候變暖，動植物物種開始大量多樣化。因此，二疊紀(jì)時期的生命是豐富多樣的。但大約2.5億年前，二疊紀(jì)時期以一次快速的大規(guī)模滅絕而結(jié)束，發(fā)生了一件事，使75%的陸地動物和95%以上的海洋生物滅絕。那是什么？是什么導(dǎo)致了這一切。好吧，有了所有的證據(jù)表明是一顆小行星導(dǎo)致了恐龍滅絕，我們開始問自己：有可能是另一顆小行星更早地導(dǎo)致了二疊紀(jì)滅絕嗎？因此，研究人員一直在尋找撞擊坑。女學(xué)生：我認(rèn)為二疊紀(jì)滅絕是由海水含氧量下降引起的。這不是課本上的內(nèi)容嗎？男教授：但別忘了教科書很清楚這只是一個理論。女學(xué)生：它也提到了火山爆發(fā)。男教授：是的，但現(xiàn)在這一新理論導(dǎo)致了對小行星撞擊證據(jù)的研究。一個有趣的地方是南極洲東部的威爾克斯島。幾年前，一位研究人員報告了威爾克斯島冰層下的一個奇怪異常。可能是mascon的證據(jù)。這只是質(zhì)量濃度的縮寫。當(dāng)小行星撞擊地球時，當(dāng)它撞擊地殼時，我們認(rèn)為這會導(dǎo)致地表深處的熔融巖石上升到撞擊區(qū)域。有點像如果你撞到你的頭，你的皮膚下會有一個大腫塊。流體使該區(qū)域膨脹。不管怎樣，從地殼下面向上流動的物質(zhì)比地殼本身密度更大。這就是我們?nèi)绾蔚玫揭粋€mascon，地殼中的一個點，有較新的地殼材料，比周圍的材料密度更高。月球上也有很多mascon，mascon的密度會導(dǎo)致局部重力的小幅度增加，這可以通過軌道航天器測量和繪制。而這些Mascon往往在哪里找到？在月球表面撞擊坑的中心。但回到威爾克斯莊園。我們不確定那里的黑子…可能是黑子…實際上是小行星撞擊造成的，但似乎有證據(jù)。研究人員注意到了一個類似于月球上的重力異常。重力讀數(shù)特別高的地方……這正是一個500公里寬的圓形山脊的中間，可能是一個古老的撞擊坑的一部分。如果威爾克斯島上有小行星撞擊，下一個問題是：它發(fā)生在2.5億年前嗎？因為這會把它放在地質(zhì)史上？

女學(xué)生：在二疊紀(jì)末期？就在那些動物滅絕的時候。男教授：沒錯。

女學(xué)生：但研究人員難道不能通過研究威爾克斯島上的巖石得出這個結(jié)論嗎……這一撞擊應(yīng)該發(fā)生在哪里？男教授：好吧，要想從很久以前找到任何東西，我們必須鉆到大約一英里，大約1.6公里的固體冰，覆蓋今天的區(qū)域。這不太可能發(fā)生。但說到巖石，我應(yīng)該提到威爾克斯莊園不是這里唯一的名勝。在澳大利亞海岸有另一個叫貝多特高地的地方。我們有貝多特高地的巖石樣本。有些顯然是地外起源的。我的意思是，它們顯示了極端溫度和壓力的影響，只有沖擊才會產(chǎn)生極端水平。至于它們的年齡，事實上，它們可以追溯到大約2.5億年前。

三、Permian Extinction托福聽力問題：

Q1:1.What does the professor mainly discuss?

A.New evidence about what happened to dinosaurs

B.New methods for gathering evidence about mass extinctions

C.The link between two mascons from the Permian period

D.A possible cause of the Permian extinction

Q2:2.According to the professor,why did researchers begin looking for evidence that an asteroid may have caused the Permian extinction?

A.They discovery that mascons on the Moon were caused by asteroid impacts.

B.They found rock samples in Wilkes Land that appeared to be 250 million years old.

C.The theory that an asteroid caused the dinosaur extinction gained acceptance.

D.The theory about a decline in seawater oxygen levels proved to be false.

Q3:3.Why does the professor mention getting a bump on the head?

A.To help students understand an explanation of how a mascon forms

B.To illustrate a theory about how the supercontinent broke apart

C.To show the relationship between an asteroid and the dinosaur extinction

D.To compare the dinosaur extinction to the Permian extinction

Q4:4.What did researchers notice that could be evidence of an asteroid impact in Wilkes Land?

A.A ring of ice containing a high concentration of oxygen

B.A portion of Earth's crust that is less dense than normal

C.Extraterrestrial rock fragments lying below the ice

D.Relatively high gravity measurements in the center of a circular ridge

Q5:5.What does the professor emphasize about some of the rock samples taken from the Bedout High near Australia?[Click on 2 answers.]

A.They are similar to the samples from the Yucatán peninsula in Mexico.

B.They are from the same time period as the Permian extinction.

C.They have been exposed to extreme temperatures and pressure.

D.They contain fossils of many species that are now extinct.

Q6:6.What does the professor imply when he says this:

A.The student should read the assignments before coming to class.

B.The student has not fully understood a statement in the textbook.

C.The student has not provided sufficient evidence to disprove the theory in the textbook.

D.The only reasonable explanation is the theory that the student suggests.

四、Permian Extinction托福聽力答案：

A1:正確答案：D

A2:正確答案：C

A3:正確答案：A

A4:正確答案：D

A5:正確答案：BC

A6:正確答案：B

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