『新东方在线托福阅读』为托福考生准备了ETS托福TPO/Official 4 Passage 3阅读练习：In paragraph 6, the author’s primary purpose is to真题题目及答案解析，TPO/Official 4 Passage 3阅读原文范文音频翻译

托福TPO/Official 4 Passage 3阅读原文In paragraph 6, the author’s primary purpose is to题目答案及解析-新东方托福官方网校手机版

石油，由原油和天然气组成，似乎起源于海洋沉积物中的有机物。

Petroleum, consisting of crude oil and natural gas, seems to originate from organic matter in marine sediment.

微观生物沉降到海底并积聚在海洋泥浆中。

Microscopic organisms settle to the seafloor and accumulate in marine mud.

有机物可能会部分分解，从而耗尽沉积物中的溶解氧。

The organic matter may partially decompose, using up the dissolved oxygen in the sediment.

一旦氧气消失，腐烂就停止了，剩余的有机物得以保留。

As soon as the oxygen is gone, decay stops and the remaining organic matter is preserved.

持续的沉积--沉积物在海底沉降的过程--会掩埋有机物，并使有机物经受更高的温度和压力，从而将有机物转化为石油和天然气。

Continued sedimentation—the process of deposits’ settling on the sea bottom—buries the organic matter and subjects it to higher temperatures and pressures, which convert the organic matter to oil and gas.

当泥泞的沉积物被压在一起，气体和少量油滴可能会从泥浆中被挤出来，并可能进入到附近的沙层中去。

As muddy sediments are pressed together, the gas and small droplets of oil may be squeezed out of the mud and may move into sandy layers nearby.

在很长一段时间（数百万年）里，天然气和石油会累积起来，积聚在沙层中。

Over long periods of time (millions of years), accumulations of gas and oil can collect in the sandy layers.

石油和天然气的密度都低于水，因此它们通常会通过水饱和的岩石和沉积物向上升。

Both oil and gas are less dense than water, so they generally tend to rise upward through water-saturated rock and sediment.

地下石油聚集在一起，就形成了宝贵的油床，而由一个或多个油床所覆盖区域，就叫做油田。

Oil pools are valuable underground accumulations of oil, and oil fields are regions underlain by one or more oil pools.

当油床或油田被发现后，人们就会钻井入地。

When an oil pool or field has been discovered, wells are drilled into the ground.

建造固定塔，也就是井架，是为了控制长段钻杆。

Permanent towers, called derricks, used to be built to handle the long sections of drilling pipe.

现在，便携式钻孔机安装和使用后，就会被拆除带走。

Now portable drilling machines are set up and are then dismantled and removed.

当油井到达油床时，油会上升，这是油水二者的密度差异或滞留在其上方的膨胀气体的压力造成的。

When the well reaches a pool, oil usually rises up the well because of its density difference with water beneath it or because of the pressure of expanding gas trapped above it.

尽管现在，油上升的现象已经几乎被控制住了，但过去，经常发生井喷和管涌。

Although this rise of oil is almost always carefully controlled today, spouts of oil, or gushers, were common in the past.

气压逐渐消失，油从井中抽出来。

Gas pressure gradually dies out, and oil is pumped from the well.

水或蒸汽可以被泵送到相邻的井中，以帮助将油排出。

Water or steam may be pumped down adjacent wells to help push the oil out.

在一家炼油厂，地下的原油被分离成天然气，汽油，煤油和各种油。

At a refinery, the crude oil from underground is separated into natural gas, gasoline, kerosene, and various oils.

染料，肥料和塑料等石化产品也由石油制成。

Petrochemicals such as dyes, fertilizer, and plastic are also manufactured from the petroleum.

随着寻找石油变得越来越困难，石油勘探活动已扩展到更恶劣的环境中。

As oil becomes increasingly difficult to find, the search for it is extended into more-hostile environments.

要想发现新的油田，要斥巨资，难度也颇大，阿拉斯加北坡油田的开发和阿拉斯加管道的建设就是一个例子。

The development of the oil field on the North Slope of Alaska and the construction of the Alaska pipeline are examples of the great expense and difficulty involved in new oil discoveries.

海上钻井平台将对石油的搜寻范围扩展到了海洋的大陆架上，也就是在大陆边缘缓缓倾斜的海底部分。

Offshore drilling platforms extend the search for oil to the ocean’s continental shelves—those gently sloping submarine regions at the edges of the continents.

虽然近海钻井比陆上钻井成本高六至七倍，但世界上四分之一以上的石油和近五分之一的天然气都来自近海。

More than one-quarter of the world’s oil and almost one-fifth of the world’s natural gas come from offshore, even though offshore drilling is six to seven times more expensive than drilling on land.

这些石油和天然气的很大一部分都来自英国和挪威之间的北海。

A significant part of this oil and gas comes from under the North Sea between Great Britain and Norway.

当然，还有很多地下石油等待我们去发掘。

Of course, there is far more oil underground than can be recovered.

它们有的面积不够大或者距离潜在市场地太远，考虑到它的开采成本，开采这些油床就不划算了。

It may be in a pool too small or too far from a potential market to justify the expense of drilling.

一些石油位于禁止钻探的区域，例如国家公园或其他公共土地。

Some oil lies under regions where drilling is forbidden, such as national parks or other public lands.

即使采用最好的提取技术，给定油藏中只有约30％至40％的油可以被带至地表。

Even given the best extraction techniques, only about 30 to 40 percent of the oil in a given pool can be brought to the surface.

其余的东西很难提取，只能留在地下。

The rest is far too difficult to extract and has to remain underground.

此外，将石油从地下和海底运送至消费者的管道沿线的任何地方都有可能出现环境问题。

Moreover, getting petroleum out of the ground and from under the sea and to the consumer can create environmental problems anywhere along the line.

输送石油的管道可能会因断层或山体滑坡而破裂，从而导致严重的石油泄漏。

Pipelines carrying oil can be broken by faults or landslides, causing serious oil spills.

油船，也就是那些巨大的载油货船，若被撞击或意外搁浅（如1989年阿拉斯加油船事件）会在海上产生浮油。

Spillage from huge oil-carrying cargo ships, called tankers, involved in collisions or accidental groundings (such as the one off Alaska in 1989) can create oil slicks at sea.

海上平台也可能会泄露石油，形成浮油，这些浮油会飘上岸并污染海滩，从而危害环境。

Offshore platforms may also lose oil, creating oil slicks that drift ashore and foul the beaches, harming the environment.

有时，油田的地面可能会因为油被抽走了而下陷。

Sometimes, the ground at an oil field may subside as oil is removed.

加利福尼亚州长滩附近的威明顿油田在50年中下陷了9米；人们只能通过建造防护屏障来防止海水倒灌。

The Wilmington field near Long Beach, California, has subsided nine meters in 50 years; protective barriers have had to be built to prevent seawater from flooding the area.

最后，石油及其产品的精炼和燃烧会造成空气污染。

Finally, the refining and burning of petroleum and its products can cause air pollution.

不过，先进的技术和严格的法律正在帮助控制一些对环境的破坏。

Advancing technology and strict laws, however, are helping control some of these adverse environmental effects.

According to paragraph 1, which of the following is true about petroleum formation?

In paragraphs 1 and 2, the author’s primary purpose is to

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

Which of the following can be inferred from paragraph 3 about gushers?

Which of the following strategies for oil exploration is described in paragraph 4?

What does the development of the Alaskan oil field mentioned in paragraph 4 demonstrate?

According to paragraph 5, the decision to drill for oil depends on all of the following factors EXCEPT

In paragraph 6, the author’s primary purpose is to

Look at the four squares  that indicate where the following sentence could be added to the passage. Unless something acts to halt this migration, these natural resources will eventually reach the surface.  Where would the sentence best fit? Click on a square  to add the sentence to the passage.

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Petroleum Resources Petroleum, consisting of crude oil and natural gas, seems to originate from organic matter in marine sediment. Microscopic organisms settle to the seafloor and accumulate in marine mud. The organic matter may partially decompose, using up the dissolved oxygen in the sediment. As soon as the oxygen is gone, decay stops and the remaining organic matter is preserved. Continued sedimentation—the process of deposits’ settling on the sea bottom—buries the organic matter and subjects it to higher temperatures and pressures, which convert the organic matter to oil and gas.  As muddy sediments are pressed together, the gas and small droplets of oil may be squeezed out of the mud and may move into sandy layers nearby.  Over long periods of time (millions of years), accumulations of gas and oil can collect in the sandy layers.  Both oil and gas are less dense than water, so they generally tend to rise upward through water-saturated rock and sediment.  Oil pools are valuable underground accumulations of oil, and oil fields are regions underlain by one or more oil pools. When an oil pool or field has been discovered, wells are drilled into the ground. Permanent towers, called derricks, used to be built to handle the long sections of drilling pipe. Now portable drilling machines are set up and are then dismantled and removed. When the well reaches a pool, oil usually rises up the well because of its density difference with water beneath it or because of the pressure of expanding gas trapped above it. Although this rise of oil is almost always carefully controlled today, spouts of oil, or gushers, were common in the past. Gas pressure gradually dies out, and oil is pumped from the well. Water or steam may be pumped down adjacent wells to help push the oil out. At a refinery, the crude oil from underground is separated into natural gas, gasoline, kerosene, and various oils. Petrochemicals such as dyes, fertilizer, and plastic are also manufactured from the petroleum. As oil becomes increasingly difficult to find, the search for it is extended into more-hostile environments. The development of the oil field on the North Slope of Alaska and the construction of the Alaska pipeline are examples of the great expense and difficulty involved in new oil discoveries. Offshore drilling platforms extend the search for oil to the ocean’s continental shelves—those gently sloping submarine regions at the edges of the continents. More than one-quarter of the world’s oil and almost one-fifth of the world’s natural gas come from offshore, even though offshore drilling is six to seven times more expensive than drilling on land. A significant part of this oil and gas comes from under the North Sea between Great Britain and Norway. Of course, there is far more oil underground than can be recovered. It may be in a pool too small or too far from a potential market to justify the expense of drilling. Some oil lies under regions where drilling is forbidden, such as national parks or other public lands. Even given the best extraction techniques, only about 30 to 40 percent of the oil in a given pool can be brought to the surface. The rest is far too difficult to extract and has to remain underground. Moreover, getting petroleum out of the ground and from under the sea and to the consumer can create environmental problems anywhere along the line. Pipelines carrying oil can be broken by faults or landslides, causing serious oil spills. Spillage from huge oil-carrying cargo ships, called tankers, involved in collisions or accidental groundings (such as the one off Alaska in 1989) can create oil slicks at sea. Offshore platforms may also lose oil, creating oil slicks that drift ashore and foul the beaches, harming the environment. Sometimes, the ground at an oil field may subside as oil is removed. The Wilmington field near Long Beach, California, has subsided nine meters in 50 years; protective barriers have had to be built to prevent seawater from flooding the area. Finally, the refining and burning of petroleum and its products can cause air pollution. Advancing technology and strict laws, however, are helping control some of these adverse environmental effects.