托福阅读讲解

托福阅读讲解

 

In 1979 James Lovelock, a British atmospheric chemist, published a book that proposes that the Earth is a single living entity. This is known as the G Hypothesis and it suggests that Gaia, or Mother Earth, is alive. He developed this hypothesis in the 1960s and it gained enormous interest due to the space flights when astronauts brought back with them pictures that allowed us to view Earth for the first time from outer space. Practically glowing blue and white, the Earth really did look alive compared to other planets such as its dark and lifele looking neighbor, Mars

 

According to his hypothesis the various components that make up the planet such as the atmosphere, the seas etc., are in balance. This is much like the homeostatic condition within the human body where a constant temperature and blood PH is maintained through various processes controlled by the liver,kidneys etc.

 

The idea of the Earth being alive has brought new awareness to the impact that man has on global processes. Everything that happens on the planet from the deforestation of trees, the increase of emissions of carbon dioxide to the removal of croplands all have an effect on our planet. We can no longer think of pollution in one part of the planet as being distinct from another part; it is all related. No longer can governments sit back and happily state that their pollution levels are lower than other countries because what goes on in say India, the United States or even Timbuktu will affect what goes on anywhere else on the planet.

 

Lovelock stated that the planet regulates itself just like the human body. If our body temperature rises above a desirable level then the body sweats to cool itself down. Lovelock suggested that this can be compared to the fact that the heat of the sun has increased a lot since life began on Earth but the planet has maintained the same temperature. So how does it do this? A good example is the carbon dioxide cycle. Volcanoes constantly produce massive quantities of carbon dioxide. Carbon dioxide is a greenhouse gas and so naturally warms the Earth. If we don't sweat to cool ourselves down, then our temperatures will continue to increase with a disastrous effect. Just like our bodies, if the Earth's temperature is not regulated then soon enough it would not be able to support life. While plants and animals absorb and release carbon dioxide through life processes such as photosynthesis, respiration and decay, these processes don't have any effect upon total amount of the gas.

 

Rock weathering is a process by which carbon dioxide is removed from the atmosphere. Rainwater and carbon dioxide combine with rocks and form carbonates, which are washed away into the ocean, where microscopic algae make tiny shells by using them. When the algae are dead, their shells sink to the bottom of the occan and form limestone sediments. Limestone has comparatively great physical weight, so it gradually sinks underneath the Earth's mantle and melts there. The carbon dioxide within the limestone in turn will be returned to the atmosphere through a bout of volcanic activity. Since soil bacteria are more active in high temperatures, the removal of carbon dioxide acts faster when the planet is hot. This has the effect of cooling the planet, completing the cycle.

 

But if it is true as Lovelock suggests that the Earth self regulates, we can assume that it does not respond to environmental stresses in a simple way. The amount of solar energy the Earth has received over thousands of years has fluctuated and these fluctuations have produced complex climatic changes between cold Ice Age episodes and warmer interglacial periods during the last 2million years.

 

Since the Industrial Revolution in the 19th Century, man has released huge amounts of pollutants into the atmosphere in a relatively short period of time.Evidence from carbon dioxide in air bubbles trapped in ice shows that the amount of CO2 in the air has increased by about a quarter since. As the Earth experiences more and more stresses in the form of increased pollution from natural and man made activities, just how the Earth will react could yield abrupt and dramatic climatic change. What took thousands of years to bring about the Ice Age could take a far lesser time today.

 

There is no proof yet, however, to support Lovelock's Gaia hypothesis and while it has attracted a lot of interest, it also received a lot of criticism. But despite this, Lovelock's hypothesis has changed the way we view our planet. Through his theories, we are far more aware of the damage we are doing to the Earth and we now see the Earth as a living entity.

Question 1:

What is the main idea of the passage?

A When man realized how beautiful Earth is from outer space, it changed our attitude toward our life.

B The Earth is like any other living organism and has an inbuilt survival mechanism.

C Man-made pollution is pushing the Earth to its absolute limits.

D If man does not halt all poisonous emissions immediately then the Earth will enter another Ice Age.

 

Question 2:

What is the main idea of paragraph 1?

A All other planets look lifeless compared to Earth.

B No one realized that Earth looks alive from outer space.

A new concept of Earth as a living being was introduced.

D If the Earth is alive then it will struggle to survive.

 

Question3:

What is the main idea of paragraph 2?

A The Earth maintains condition necessary for its survival.

B By figuring out human physiology we can understand our planet better.

C Plants and animals act as Earth's senses.

D Increased pollution interferes with Earth's climatic rhythms

 

Question4:

What is the main idea of paragraph 3?

A Timbuktu's pollution levels will affect anywhere else on the planet.

B Lovelock's hypothesis has brought governments together in our global fight gainst pollution.

C Governments don't care about pollution levels in other countries and refuse to dis-cuss a global environmental strategy.

D Deforestation is adversely affecting the croplands of the planet and this might reduce their annual yield.

 

Question 5:

What is the main idea of paragraph 4?

A The sun is emitting very dangerous levels of radiation.

B Volcanoes emit the highest amount of carbon dioxide.

C The Earth self-regulates and maintains a balance.

D Carbon dioxide warms the planet.

 

Question6:

What is the main idea of paragraph 5?

A Limestone is so heavy that it melts but sometimes it escapes into the air.

B Carbon dioxide is removed from the atmosphere by natural processes.

C Volcanoes emit carbon dioxide from limestone by natural processes.

D When the planet is hot, bacteria will produce more carbon dioxide.

 

Question 7:

What is the main idea of paragraph 6?

A There have been many ice ages during the last 2 million years.

B Scientists are expecting another Ice Age very soon

Interglacial periods are caused by solar fluctuations.

D The Earth does not respond well to environmental stress.

 

Question 8:

What is the main idea of paragraph 7?

A We cannot predict how the Earth will respond to increased pollution.

B The Industrial Revolution sparked mass pollution

Carbon dioxide levels have increased dramatically since the 18th century.

D We can measure pollution levels by air bubbles trapped in ice.

 

Question 9:

What is the main idea of paragraph 8?

A Not many scientists believe Lovelock's hypothesis.

B Lovelock's hypothesis has changed the way we look at the Earth.

C Lovelock's hypothesis will help us survive environmental disaster.

D Lovelock's hypothesis will help reduce harmful emissions of pollutants.

 

问题1:文章的主题是什么？

A.当人类发现在太空中看到的地球有多么漂亮时，改变了我们对我们生活的态度。

B.地球像任何其他的有机体一样有内部的生存机制。

C.人为的污染把地球推向了极限。

D.假如人类不立即停止有毒物的排放，地球就会立即进入下一个冰河纪。

答案：B

 

问题2:第一段的主题是什么？

A.和地球机比，所有人把行星都看起来毫无生气。

B.提出了地球是有生命的实的地球就像是有生命的。

C.提出了地球是有生命的胜利，我们可以更家了解地球。

D.如果地球是有生命的，她将挣扎着不概念。

答案：C

 

问题3:第二段的主题是什么？

A.地球维持着生存的必须条件。

B.通过理解人类的生理，我们可以更加了解地球。

C.植物和动物担当着地球的感觉器官。

D.污染的增场担当着地球的感觉器官。

答案：A

 

问题4:第三段的主题是什么？

A.廷巴克图的污染状况会影响世界上任何其他地区

B.洛夫洛克假说使政府齐心协力进行全世界范围内对抗污染的斗争。

C.政府不管其他国家的污染水平，拒绝谈论地球环境战略。

D.森林采伐对地球的农耕地产生负面影响，这种影响可能减少年均生产量。

答案：B

 

问题5:第四段的主题是什么？

A.太阳会放射出非常危险的辐射能量。

B.火山释放大量的二氧化碳。

C.地球会自我调节，维持平衡。

D.二氧化碳使地球变暖。

答案：C

 

问题6:第五段的主题是什么？

A.石灰石很重，以至于会熔化，有时候还会蒸发到空气中。

B.二氧化碳通过自然的过程会从大气中移除掉

C.火山通过自然变化释放石灰石中的二氧化碳

D.地球很热时，细菌会产生更多二氧化碳。

答案：B

 

问题7:第六段的主题是什么？

A.过去的200万年间有很多的冰河时期。

B.科学家们预计马上会出现下一次冰河时期。

C.间冰期是太阳的变动而引起的

D.地球适应环境压力不够好。

答案：D

 

问题8:第七段的主题是什么？

A.我们无法预测地球对污染增加的反应方式。

B.产业革命引起了大量的污染。

C.18世纪以来，二氧化碳的量急剧增加。

D.可以用冰块中的气泡来测定污染程度。

答案：A

 

问题9:第八段的主题是什么？

A.相信洛夫洛克的假说的科学家不太多。

B.洛夫洛克的假说改变了我们看待地球的方式。

C.洛夫洛克的假说会帮助我们应对环境灾难。

D.洛夫洛克的假说会帮助减少有害污染物的排放。

答案：B