TTGWD2-Q8,Q9

huangluyao

Scientists generally credit violent collisions between tectonic plates, the mobile fragments of Earth’s rocky outer shell, with sculpting the planet’s surface, as, for example, when what is now the Indian subcontinent collided with Asia, producing the Himalayan
                    Mountains. However, plate tectonics cannot fully explain certain massive surface features, such as the “superswell” of southern Africa, a vast plateau over 1,000 miles across and nearly a mile high.
Geologic evidence shows that southern African has been slowly rising for the past 100 million years, yet it has not experienced a tectonic collision for nearly 400 million years. The explanation may be in Earth’s mantle, the layer of rock underlying the tectonic plates and extending down over 1,800 miles to the outer edge of Earth’s iron core.




Since the early twentieth century, geophysicists have understood that the mantle churns and roils like a thick soup.
The relative low density of the hottest rock makes that material buoyant, so it slowly ascends, while cooler, denser rock sinks until heat escaping the molten core warms it enough to make it rise again.
While this process of convection was known to enable the
horizontal movement of tectonic plates, until recently geophysicists were skeptical of its ability to lift or lower the planet’s surface vertically. However, recent technological advances have allowed geophysicists to make three-dimensional “snapshots” of the mantle by measuring vibrations, or seismic waves, set in motion by earthquakes originating in the planet’s outer shell and recording the time it takes for them to travel from an earthquake’s epicenter to a particular recording station at the surface.
Because geophysicists know that seismic waves become sluggish in hot, low-density rock, and speed up in colder, denser regions, they can now infer the temperatures and densities in a given segment of the interior.
By compiling a map of seismic velocities from thousands of earthquakes across the globe, they can also begin to map temperatures and densities throughout the mantle.
These methods have revealed some unexpectedly immense formations in the deepest parts of the mantle; the largest of these is a buoyant mass of hot rock directly below Africa’s southern tip.
Dispelling researchers’ initial doubts, computer models have confirmed that this formation is buoyant enough to rise slowly within the mantle and strong enough to push Africa upward as it rises.

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Q8:


In line 10, the author mentions the Himalayan
                    Mountains most likely in order to

A.
highlight certain similarities between the southern African superswell and other massive features on Earth’s surface

B.
identify a feature of Earth’s surface that predates the origins of the southern African superswell

C.
provide an example of a feature of Earth’s surface that can explained by plate tectonics

D.
suggest that geophysicists are correct in attributing the sculpting of Earth’s surface to violent collisions between tectonic plates

E.
give an example of a feature of Earth’s surface that scientists are unable to explain fully

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answer is C, why not E

Q9:


According to the passage, the computer models referred to in line 86 have had which of the following effects?

A.
They have confirmed researchers’ doubts regarding the theory that convection within the mantle can lift or lower Earth’s surface vertically.

B.
They have cast doubt on the validity of plate-tectonics theory as an explanation for the sculpting of Earth’s mountain ranges.

C.
They have proved geophysicists’ theory that the behavior of seismic waves in Earth’s mantle is related to the temperature of the rock through which they are traveling.

D.
They have convinced formerly skeptical researchers that rock formations deep in Earth’s mantle below southern Africa could have created the superswell.

E.
They have confirmed researchers’ speculation that masses of hot rock are buoyant enough to rise to the upper part of Earth’s mantle.

answer is D, why not E

windows10

我也选e了，顶

nieyuhang

Q8 选C,不选E的理由在，plate tectonics已经能够完全解释himalayas的成因的。看原句在 Himalayan Mountains 之后的however是在说其他有些地质现象不能用板块学说来解释，比如说superswell.Scientists  ... producing the Himalayan
    Mountains. However, plate tectonics cannot fully explain certain massive surface features, such as the “superswell” of southern Africa
Q9 选D,
D & E是很相似，关键要找出两个选项的差异点D.
They have convinced formerly skeptical researchers that rock formations deep in Earth’s mantle below southern Africa could have created the superswell.

E.
They have confirmed researchers’ speculation that masses of hot rock are buoyant enough to rise to the upper part of Earth’s mantle.

两个选项的前半句，都挺好的，E似乎还更客观点;所以我们要比较后面，E选项这样就出现问题了。原文最后一句明显说了这个formation的两个特点

1. buoyant enough to rise, 2. strong enough to push

E only covers the 1 point. and it leaves D the best answer.

xiruiming

8 C前面说了一个现象能解释xx，举例说明Himalayan Mountains的形成就是这样的。

Scientists generally credit violent collisions between tectonic plates, the mobile fragments of Earth’s rocky outer shell, with sculpting the planet’s surface, as, for example, when what is now the Indian subcontinent collided with Asia, producing the Himalayan
                Mountains.

provide an example=for example 就凭这个词就该选

9 Dispelling researchers’ initial doubts, computer models have confirmed that this formation is buoyant enough to rise slowly within the mantle and strong enough to push
Africa upward as it rises.

The explanation may be in Earth’s mantle, the layer of rock underlying the tectonic plates


The relative low density of the hottest rock
makes that material buoyant, so it slowly ascends, while cooler, denser rock sinks until heat escaping the molten core warms it enough to make it rise again.

until recently geophysicists were skeptical ofits ability to lift or lower the planet’s surface vertically.

说的是rock make让那些material 浮起来，升上去，不是rock本身，E错了。




Dispelling researchers’ initial doubts, computer models have confirmed that this formation is buoyant enough to rise slowly within the mantle and strong enough to push
Africa upward as it rises.

The explanation may be in Earth’s mantle, the layer of rock underlying the tectonic plates


The relative low density of the hottest rock
makes that material buoyant, so it slowly ascends, while cooler, denser rock sinks until heat escaping the molten core warms it enough to make it rise again.

until recently geophysicists were skeptical ofits ability to lift or lower the planet’s surface vertically.

说的是rock make让那些material 浮起来，升上去，不是rock本身，E错了。

mereimoun

第9题答案我选E

答案为什么 D 呢? 还是不很懂呢?

哪位NN能解释一下呀!

LIANGSHAN

They have confirmed researchers’ speculation that masses of hot rock are buoyant enough to rise to the upper part of Earth’s mantle
这两块文章都没提。
They have convinced formerly skeptical researchers that rock formations deep in Earth’s mantle below southern Africa could have created the superswell
这两块分别是confirmed和doubts的改写。

xiaoxiangxixi

疑问：confirm one's speculation/doubts指的是让人不再怀疑还是肯定了他们的怀疑呢？

grassgreen

我觉得应该选B啊，文章里有原话：
While this process of convection was known to enable the  horizontal movement of tectonic plates, until recently geophysicists were skeptical of its ability to lift or lower the planet’s surface vertically.