Questions 11 to 13 are based on the following passage.

I’m glad you brought up the question of our investigations into the makeup of the earth’s interior. Since this is the topic of your reading assignment for next time, let me spend these last few minutes of class talking about that.

(13) There were several important discoveries in the early part of the century to help geologists develop a more accurate picture of the earth's interior. The first key discovery had to do with seismic waves. Remember, they are the vibrations caused by earthquakes. Well, scientists found that they travel thousands of miles through the earth’s interior. This finding enabled geologists to study the inner parts of the earth.

You see, these studies revealed that these vibrations were of two types： compression or P waves and shear or S waves. And researchers found that (11) P waves travel through both liquids and solids while S waves travel through only solid matter. In 1906，a British geologist discovered that P waves slowed down at a certain depth but kept traveling deeper. On the other hand, S waves either disappeared or were reflected back. So he concluded that (12) the depth marked the boundary between a solid mantle and the liquid core. Three years later, (12) another boundary was discovered that between the mantle and the earth’s crust.

There is still a lot to be learned about the earth. For instance, (12) geologists know that the core is hot. Evidence of this is the molten lava that flows out of volcanoes. (12) But we are still not sure what the source of the heat is.

 

题目

Passage 7

In this section you will hear several passages ? Listen to the passages carefully and then answer the questions that follow.

Questions 11 to 13 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions.

Now, listen to the passage.

11. P waves are different from S waves in that .

A. P waves can travel through solid matter

B. P waves can travel through liquids

C. P waves travel slower than S waves

D. S waves go deeper in the earth’s interior

12. We are still unsure of .

A. the boundary between the mantle and the earth’s core

B. the boundary between the mantle and the earth’s crust

C. where the heat of the earth core is from

D. whether the earth core is hot or not

13. What is the passage mainly about?

A. The internal constitution of the earth.

B. The difference between P waves and S waves.

C. Several important discoveries in the early 20th century.

D. The study of earth’s interior with the aid of geological discoveries.

 

答案解析

Passage 7

11.  B细节题。录音中提到P波可通过液体及固体介质，而S波只能通过固定物质， 由此可知P波与S波的不同点在于B。

12.  C细节题。注意题干关键词unsure，能证实的表述肯定不选。A“地幔与地核的分 界线”、B“地幔与地壳的分界线”都通过运用P波与S波找到了。D“地核是热的”有 火山溶岩作证。只有C尚未确定，录音中提及But we are still not sure what the source of the heat is，C是对这句话的同义转述，选C。

13. D主旨题。首先排除B，因为B讲的是细节问题。录音中很多次提到discoveries 和earth，整合这两点答案为D。