托福听力答案

12月24日 1  What is the main purpose of the lecture? A. To explain why scientists disagree about the age of the Moon B. To present arguments in favor of another Moon landing C. To explain how scientists discovered a crater on the far side of the Moon D. To review some finding of a recent mission to the Moon 2 What does the professor imply about the spacecraft Clementine? A. It sent back the first color photographs of the Moon B. It was powered by solar energy C. It landed in the far side of the Moon D. It flew over the Moon’s polar regions  3  Why does the professor mention the Moon’s mantle? A. To explain why scientists believe that meteor impacts cannot affect the Moon’s mantle B. To explain what kind of information scientists hope to obtain from the mantle C. To point out that the Moon’s crust and mantle are made of similar materials D. To point out that the Moon’s mantle and Earth’s mantle have different compositions 4  Why is the South Pole-Aitken Basin thought to be exceptionally old? A. The walls of the Basin are more reflective than those of most other craters B. Testing of rocks from the Basin’s floor proves them to be as old as the Moon itself C. Many small craters have been detected at the bottom of the Basin D. A large amount of dust has been detected in and around the Basin 5 Why does the professor consider it important to find out if water ice exists on the Moon? Click on 2 answers. A. Water ice could be processed to provide breathable air for astronauts B. One component of water ice could be used as a fuel for rockets C. Water ice could contain evidence of primitive life on the Moon D. Water ice could be tested to find out what type of meteors crashed into the Moon  Astronomy Narrator：Listen to part of a lecture in an Astronomy Class Professor：Last week, we covered some arguments against going back to the Moon. But there are compelling reasons in favor of another Moon landing too, um… not the least of which is trying to pinpoint the moon’s age. We could do this in theory by studying an enormous impact crater, known as the South Pole-Aitken Basin. Um…it’s located in the moon’s South Polar Region. But, since it’s on the far side of the moon, it can only be seen from space. Here is an image of…we’ll call it the SPA Basin. This color-coated image of the SPA Basin, those aren’t its actual colors obviously, this image is from the mid 90s, from the American spacecraft called Clementine. Um… unlike earlier lunar missions, Clementine didn’t orbit only around the moon’s equator. Its orbits enable it to send back data to create this topographical map of … well, the grey and white area towards the bottom is the South Pole, the purples and blues in the middle correspond to low elevations - the SPA Basin itself, the oranges and reds around it are higher elevations. The basin measures an amazing 2,500 km in diameter, and its average depth is 12 km. That makes it the biggest known crater in our solar system and it may well be the oldest. You know planetary researchers love studying deep craters until learn about the impacts that created them, how they redistributed pieces of a planet’s crust and in this case, we especially want to know if any of the mantle, the layer beneath the crust, was exposed by the impact. Not everyone agrees, but some experts are convinced that whatever created the SPA Basin did penetrate the Moon’s mantle. And we need to find out, because much more than the crust, the mantle contains information about a planet’s or Moon’s total composition. And that’s key to understanding planet formation. Um… Dian? Dian: So, the only way to know the basin’s age is to study its rocks directly? Professor: well, from radio survey data, we know that the basin contains lots of smaller craters. So it must be really old, about 4 billion years, give or take a few hundred million years. But that’s not very precise. If we had rock samples to study, we’d know whether the small craters were formed by impacts during the final stages of planetary formation, or if they resulted from later meteor show