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  • Permian Extinction托福听力原文翻译及问题答案

    时间:2023-07-06 09:45:35 来源:www.ivyeducation.cn

    Permian Extinction托福听力原文翻译及问题答案

    一、Permian Extinction托福听力原文:

    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托福听力中文翻译:





    三、Permian Extinction托福听力问题:

    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托福听力答案:








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