填空题
1. Much of the world gets its energy from fossil fuel sources, including coal, oil, and natural gas, all of which were created millions of years ago.The process began with dead plant and animal matter that collected and over time was buried deep within the earth. There, exposed to extreme pressure and temperatures, the carbon-based material underwent various chemical and physical changes. Some of it became coal, some oil, and some natural gas, depending on the exact conditions it was subjected to.
2. Natural gas is both invisible and odorless. During the first century of the fossil fuel era, it was disregarded as a worthless byproduct of coal and oil. However, people later discovered that it could also be a useful source of energy, and they set about trying to {{U}}realize its potential.{{/U}} Its use began to grow in the twentieth century and has increased rapidly within the last 40 years. Nowadays, natural gas is employed all over the world to heat homes, generate electricity, power factories, and even fuel vehicles.
3. Because it was created through the same process as other fossil fuels, natural gas can often be retrieved from oil fields, something known as an associated source. Coal beds have similarly been known to yield natural gas. In addition, there are isolated deposits containing only gas that are referred to as non-associated sources. To access a subterranean natural gas pocket, a hole is drilled down into it, just as in oil extraction. However, due to the gas's lightness, it will rise to the surface on its own instead of having to be pumped out.
4. The compound we know as natural gas is actually a {{U}}composite{{/U}} of several different substances, the primary one being methane gas. Each deposit has a unique makeup, but other common components of natural gas include propane, butane, and sulfur. Borrowing terms used in the description of oil, natural gas with a high sulfur content is called "sour" while that with a low content is referred to as "sweet" Regardless of the exact composition, natural gas must be refined to remove its impurities; when ready for use, it is nearly pure methane.
5. Natural gas offers many advantages as a fuel source, the first and most important being that it is extremely clean burning. While oil and coal both have complex molecular structures, methane's is simple: one carbon atom surrounded by four atoms of hydrogen. The lack of excess particles translates into fewer waste byproducts during combustion. For example, all fossil fuels produce carbon dioxide when burned, but natural gas releases substantially less carbon dioxide than other fuels. Given the major role of carbon dioxide in the acceleration of global warming, {{U}}this{{/U}} is an important attribute. In addition, natural gas emits far less nitrogen and sulfur, which are key contributors to the smog that pollutes the air in metropolitan areas, as well as acid rain.
6. The benefits of natural gas extend far beyond its cleanliness. Since it contains fewer waste particles, its energy can be acquired with much more efficiency than that of the other fossil fuels, meaning a lower overall cost for the consumer.
Another advantage is that natural gas is
transported via underground pipelines instead of by ships and trucks. 
Finally, natural gas is relatively plentiful
and widespread. 
Geologists have
identified extensive stores in Canada, the United States, Russia, the Middle
East, and Australia, among other locations. 
Energy from Natural Gas
1. Much of the world gets its energy from fossil fuel sources, including coal, oil, and natural gas, all of which were created millions of years ago.The process began with dead plant and animal matter that collected and over time was buried deep within the earth. There, exposed to extreme pressure and temperatures, the carbon-based material underwent various chemical and physical changes. Some of it became coal, some oil, and some natural gas, depending on the exact conditions it was subjected to.
2. Natural gas is both invisible and odorless. During the first century of the fossil fuel era, it was disregarded as a worthless byproduct of coal and oil. However, people later discovered that it could also be a useful source of energy, and they set about trying to {{U}}realize its potential.{{/U}} Its use began to grow in the twentieth century and has increased rapidly within the last 40 years. Nowadays, natural gas is employed all over the world to heat homes, generate electricity, power factories, and even fuel vehicles.
3. Because it was created through the same process as other fossil fuels, natural gas can often be retrieved from oil fields, something known as an associated source. Coal beds have similarly been known to yield natural gas. In addition, there are isolated deposits containing only gas that are referred to as non-associated sources. To access a subterranean natural gas pocket, a hole is drilled down into it, just as in oil extraction. However, due to the gas's lightness, it will rise to the surface on its own instead of having to be pumped out.
4. The compound we know as natural gas is actually a {{U}}composite{{/U}} of several different substances, the primary one being methane gas. Each deposit has a unique makeup, but other common components of natural gas include propane, butane, and sulfur. Borrowing terms used in the description of oil, natural gas with a high sulfur content is called "sour" while that with a low content is referred to as "sweet" Regardless of the exact composition, natural gas must be refined to remove its impurities; when ready for use, it is nearly pure methane.
5. Natural gas offers many advantages as a fuel source, the first and most important being that it is extremely clean burning. While oil and coal both have complex molecular structures, methane's is simple: one carbon atom surrounded by four atoms of hydrogen. The lack of excess particles translates into fewer waste byproducts during combustion. For example, all fossil fuels produce carbon dioxide when burned, but natural gas releases substantially less carbon dioxide than other fuels. Given the major role of carbon dioxide in the acceleration of global warming, {{U}}this{{/U}} is an important attribute. In addition, natural gas emits far less nitrogen and sulfur, which are key contributors to the smog that pollutes the air in metropolitan areas, as well as acid rain.
6. The benefits of natural gas extend far beyond its cleanliness. Since it contains fewer waste particles, its energy can be acquired with much more efficiency than that of the other fossil fuels, meaning a lower overall cost for the consumer.
Another advantage is that natural gas is
transported via underground pipelines instead of by ships and trucks. Finally, natural gas is relatively plentiful
and widespread. Geologists have
identified extensive stores in Canada, the United States, Russia, the Middle
East, and Australia, among other locations.
单选题
According to Paragraph 1, the oil, coal, and natural gas that exist
today
【正确答案】
B
【答案解析】
单选题
The phrase realize its potential in the passage is closest in meaning
to
【正确答案】
B
【答案解析】
单选题
In Paragraph 2, the author explains that natural gas use
【正确答案】
B
【答案解析】
单选题
What can be inferred from Paragraph 3 about the extraction of natural
gas?
【正确答案】
C
【答案解析】
单选题
The word composite in the passage is closest in meaning to
【正确答案】
A
【答案解析】
单选题
According to Paragraph 4, what can be inferred about "sweet" natural
gas?
【正确答案】
D
【答案解析】
单选题
Why does the author discuss carbon dioxide's relationship to global
warming in Paragraph 5?
【正确答案】
D
【答案解析】
单选题
The word this in the passage refers to
【正确答案】
C
【答案解析】
单选题
The word emits in the passage is closest in meaning to
【正确答案】
B
【答案解析】
单选题
According to Paragraph 7, one danger of using natural gas is that
【正确答案】
B
【答案解析】
单选题
Which of the following statements most accurately reflects the
author's opinion about natural gas?
【正确答案】
A
【答案解析】
单选题
Look at the four squares [■] that indicate where the following
sentence could be added to the passage.
Not only does this ensure its protection from severe weather events and other unpredictable hazards, but it also reduces the amount of energy required to move it from place to place.
Where would the sentence best fit?
Click on a square [■] to add the sentence to the passage.
Not only does this ensure its protection from severe weather events and other unpredictable hazards, but it also reduces the amount of energy required to move it from place to place.
Where would the sentence best fit?
Click on a square [■] to add the sentence to the passage.
【正确答案】
B
【答案解析】
填空题
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.
Originally, natural gas was not considered a useful commodity and it has only become a major source of energy in the last century.
·______
·______
·______
A. Natural gas differs from other fossil fuels in that it is not found in underground deposits.
B. Natural gas is extracted from both associated and non-associated sources, and there are many different varieties.
C. Some deposits of natural gas contain high concentrations of impurities such as sulfur and cannot be used commercially.
D. Because it burns cleaner than coal and oil, natural gas is much less damaging for the environment.
E. One of the main drawbacks in the use of natural gas is that it cannot be piped across oceans.
F. Natural gas is an appealing alternative to other fossil fuels because it is cheaper, more easily transported, and more abundant.
Originally, natural gas was not considered a useful commodity and it has only become a major source of energy in the last century.
·______
·______
·______
Answer Choices
A. Natural gas differs from other fossil fuels in that it is not found in underground deposits.
B. Natural gas is extracted from both associated and non-associated sources, and there are many different varieties.
C. Some deposits of natural gas contain high concentrations of impurities such as sulfur and cannot be used commercially.
D. Because it burns cleaner than coal and oil, natural gas is much less damaging for the environment.
E. One of the main drawbacks in the use of natural gas is that it cannot be piped across oceans.
F. Natural gas is an appealing alternative to other fossil fuels because it is cheaper, more easily transported, and more abundant.