单项选择题

磁异常（magnetic anomaly）

In an age when waste today means a lack tomorrow, making use of every available resource becomes more and more important. As coal is being used in greater and greater amounts to produce electricity, larger amounts of ash, by-product of coal, are produced. When coal is burned in a boiler, two kinds of ash by-product are produced: a heavy bottom ash and a fine-as-powder fly ash that is filtered and captured by precipitators. About 10 to 15 percent of the coal by-product is bottom ash which is used like sand on icy city streets and highways and also on highways as paving material. It is the fly ash, however, that is receiving the greater amount of attention. Fly ash may be used as an additive to concrete in the construction of dams, bricks, and roads, and can replace up to 20 percent of the cement used in concrete. As a by-product of burned coal, fly ash requires no additional expenditure of energy to be produced, while cement production requires great amounts of energy.
In addition to using fly ash as a concrete additive, the technology is available to extract the main mineral components-aluminum, silicon, and magnetic. Today, extracting these components is a very expensive process, but the time may come when it is cheaper to extract these products from ash than to mine new supplies.

What can be extracted from fine-powder fly ash（　）

A:Aluminum, silicon, and magnetic. B:Additive. C:Paving material. D:Cement.

In order to limit the damage and to prevent some of the suffering resulting from earthquakes, scientists are working on ways to enable accurate prediction, Special instruments are used to help people record, for example, shaking of the earth. Scientist are trying to find methods that will enable them to indicate the exact time, location and size of an earthquake.
Certain phenomena have been observed which are believed to be the signs of imminent(即将发生的) earthquakes. These include strange behaviours of some animals, the changes in the content of mineral water, etc. The magnetic properties of rocks may also display special pattern before major earthquakes happen.
Signs of imminent earthquakes include all the following BUT

A:strange behaviours of animals. B:changes in the content of mineral water. C:the magnetic properties of rocks. D:dramatic change in climat

Where Did All the Ships Go

The Bermuda Triangle is one of the greatest mysteries of the sea. In this triangle area between Florida, Puerto Rico and Bermuda in Atlantic, ships and airplanes seem to disappear more of ten than in other pans of the ocean. And they do so without leaving any sign of all accident or any dead bodies.
It is said that Christopher Columbus was the first person to record strange happenings in the area. His compass stopped working, a flame came down from the sky, and a wave 100 to 200 feet high carried his ship about a mile away.
The most famous disappearance in the Bermuda Triangle was the U. S. Naval Air Flight 19. On December 5, 1945, five bomber planes carrying 14 men took offon a training mission from the Florida coast. Later that day, all communications with Flight 19 were lost. They just disappeared without a trace.
The next morning, 242 planes and 19 ships took part in the largest air-sea search in history. But they found nothing.
Some people blame the disappearances on supernatural forces. It is suggested the missing ships and planes were either transported to other times and places, kidnapped by aliens or attacked by sea creatures.
There are also natural explanations, though. The U. S. Navy says that the Bermuda triangle is one of two places on earth where a magnetic compass points towards true north instead of magnetic north. Therefore, planes and ships can lose their way if they don’t make adjustments.
The area also has changing weather and is known for its high waves. Storms can turn up suddenly and destroy a plane or ship. Fast currents could then sweep away any trace of an accident.
What will happen to the ship crossing the Bermuda Triangle according to the U. S. Navy

A:It will disappear anyway. B:Its compass will point to the true north instead of magnetic north. C:It is impossible for itto find the right way due to the magnetic effect. D:Storms will turn up suddenly and destroy the ship.

{{B}}第三篇{{/B}}

? ?There are some earth phenomena you can count on, but the magnetic field, some say, is not one of them. It fluctuates in strength, drifts from its axis, and every few 100,000 years undergoes a dramatic polarity reversal —a period when north pole becomes south pole and south pole becomes north pole. But how is the field generated, and why is it so unstable?
? ? ?Groundbreaking research by two French geophysicists promises to shed some light on the mystery. Using 80 metres of deep sea sediment (沉淀物) core, they have obtained measurements ?of magnetic-field intensity that span 11 polarity reversals and four million years. The analysis reveals that intensity appears to fluctuate with a clear, well-defined rhythm. Although the strength of the magnetic field varies irregularly during the short tern, there seems to be an inevitable long-term decline preceding each polarity reversal. When the poles flip—a process that takes several hundred thousand years--the magnetic field rapidly regains its strength and the cycle is repeated.
? ?The results have caused a stir among geophysicists. The magnetic field is thought to originate ?from molten (熔化的) iron in the outer core, 3,000 kilometers beneath the earth’s surface. ?By studying mineral grains found in material ranging from rocks to clay articles, previous researchers have already been able to identify reversals dating back 170 million years, including the most recent switch 730,000 years age. How and why they occur, however, has been widely debated. Several theories link polarity flips to external disasters such as meteor (陨星) impacts. ?But Peter Olson, a geophysicist at the Johns Hopkins University in Baltimore, says this is unlikely if the French researchers are right. In fact, Olson says intensity that predictably declines from one reversal to the nest contradicts 90 percent of the models currently under study. If the results prove to be valid geophysicists will have a new theory to guide them in their quest to understand the earth’s inner physics. It certainly points the direction for future research.
Which of the following titles is most appropriate to the passage?

A:Polarity Reversal :A Fantastic Phenomenon of Nature B:Measurement of the Earth’s Magnetic-Field Intensity C:Formation of the Two Poles of the Earth D:A New Approach to the Study of Geophysics

{{B}}第三篇{{/B}}

? ?There are some earth phenomena you can count on, but the magnetic field, some say, is not one of them. It fluctuates in strength, drifts from its axis, and every few 100,000 years undergoes a dramatic polarity reversal —a period when north pole becomes south pole and south pole becomes north pole. But how is the field generated, and why is it so unstable?
? ? ?Groundbreaking research by two French geophysicists promises to shed some light on the mystery. Using 80 metres of deep sea sediment (沉淀物) core, they have obtained measurements ?of magnetic-field intensity that span 11 polarity reversals and four million years. The analysis reveals that intensity appears to fluctuate with a clear, well-defined rhythm. Although the strength of the magnetic field varies irregularly during the short tern, there seems to be an inevitable long-term decline preceding each polarity reversal. When the poles flip—a process that takes several hundred thousand years--the magnetic field rapidly regains its strength and the cycle is repeated.
? ?The results have caused a stir among geophysicists. The magnetic field is thought to originate ?from molten (熔化的) iron in the outer core, 3,000 kilometers beneath the earth’s surface. ?By studying mineral grains found in material ranging from rocks to clay articles, previous researchers have already been able to identify reversals dating back 170 million years, including the most recent switch 730,000 years age. How and why they occur, however, has been widely debated. Several theories link polarity flips to external disasters such as meteor (陨星) impacts. ?But Peter Olson, a geophysicist at the Johns Hopkins University in Baltimore, says this is unlikely if the French researchers are right. In fact, Olson says intensity that predictably declines from one reversal to the nest contradicts 90 percent of the models currently under study. If the results prove to be valid geophysicists will have a new theory to guide them in their quest to understand the earth’s inner physics. It certainly points the direction for future research.
What have the two French geophysicists discovered in their research?

A:Some regularity in the changes of the earth’s magnetic field, B:Some causes of the fluctuation of the earth’s magnetic field, C:The origin of the earth’s magnetic field. D:The frequency of polarity reversals.

{{B}}第三篇{{/B}}

? ?There are some earth phenomena you can count on, but the magnetic field, some say, is not one of them. It fluctuates in strength, drifts from its axis, and every few 100,000 years undergoes a dramatic polarity reversal —a period when north pole becomes south pole and south pole becomes north pole. But how is the field generated, and why is it so unstable?
? ? ?Groundbreaking research by two French geophysicists promises to shed some light on the mystery. Using 80 metres of deep sea sediment (沉淀物) core, they have obtained measurements ?of magnetic-field intensity that span 11 polarity reversals and four million years. The analysis reveals that intensity appears to fluctuate with a clear, well-defined rhythm. Although the strength of the magnetic field varies irregularly during the short tern, there seems to be an inevitable long-term decline preceding each polarity reversal. When the poles flip—a process that takes several hundred thousand years--the magnetic field rapidly regains its strength and the cycle is repeated.
? ?The results have caused a stir among geophysicists. The magnetic field is thought to originate ?from molten (熔化的) iron in the outer core, 3,000 kilometers beneath the earth’s surface. ?By studying mineral grains found in material ranging from rocks to clay articles, previous researchers have already been able to identify reversals dating back 170 million years, including the most recent switch 730,000 years age. How and why they occur, however, has been widely debated. Several theories link polarity flips to external disasters such as meteor (陨星) impacts. ?But Peter Olson, a geophysicist at the Johns Hopkins University in Baltimore, says this is unlikely if the French researchers are right. In fact, Olson says intensity that predictably declines from one reversal to the nest contradicts 90 percent of the models currently under study. If the results prove to be valid geophysicists will have a new theory to guide them in their quest to understand the earth’s inner physics. It certainly points the direction for future research.
The French geophysicists’ study is different from currently prevailing theories in______.

A:its identification of the origin of the earth’s magnetic field B:the way the earth’s magnetic intensity is measured C:its explanation of the shift in the earth’s polarity D:the way the earth’s fluctuation rhythm is defined

第一篇 The Northern Lights The sun is stormy and has it own kind of weather. It is so hot and active that even the Sun’s gravity cannot hold its atmosphere in check! Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma, and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun, the stronger the solar wind. The solar wind constantly streams toward the Earth, but don’t worry because a protective magnetic fields surrounds our planet. The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles. The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth’s magnetic field first gets squeezed and then the magnetic field lines break and reconnect. The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth’s atmosphere at the poles. As the electrons fall into the Earth, they collide with gas molecules in the atmosphere, creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky, they create the Northern Lights and the Southern Lights. Watching auroras(北极光) is fun and exciting, but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate(跳动), flicker(闪烁), or even move like waves. During solar maximum, 5 auroras are seen as far south as Florida, even Mexico!Auroras often seem to be very close to the ground, but the lowest aurora is still about 100 kilometers above the ground, a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long, a few hundred kilometers high, but only a few hundred meters thick. We hope you are able to travel to far-north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it!What happens when solar wind comes to the Earth?

A:A protective magnetic field is formed at the same time. B:It is trapped in magnetic belts around the Earth. C:It destroys the protective magnetic field surrounding the Earth. D:It breaks magnetic field lines and does severe damage to the ?


下面有3篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。
{{B}}第一篇{{/B}}

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?{{B}}Sunspots{{/B}}
? ?It’s not surprising that sunspots (太阳黑子) were observed by ancient astronomers (天文学家). The largest sunspots on the sun can be seen without a telescope. It was not until the invention of the telescope (望远镜) in the early 17th century, however, that systematic studies of sunspots could be undertaken. The great astronomer Galileo was among the first to make telescopic observations of sunspots.
? ?Sunspots are regions of extremely strong magnetic fields (磁场) found on the sun’s surface. A sunspot has a dark Central core known as the umbra. The umbra is surrounded by a dark ring called the penumbra, where the magnetic field spreads outward. SunSpots appear dark because they are giving off less radiation. They are cooler than the rest of the sun’s surface.
? ?Sunspots are frequently observed in pairs or in paired groups. The members of a spot pair are identified as the leading spot and the following spot. They are identified by their position in the pair in terms of the direction in which the sun rotates (旋转).
? ?The number of sunspots at any one time varies. A large spot group may consist of as many as 10 groups and 300 spots across the sun. The number of spots changes in a fairly regular pattern called the sunspot cycle. The largest number occurs about every 11 years. At sunspot minimum, there are at most just a few small spots.
? ?The average lifetime of an individual spot group is roughly one solar rotation, which is about 25 days. The most persistent large spots,’ however, can survive for two to three months.
Sunspots are cooler than the rest of the sun’s surface because

A:they produce less energy B:they are buried in the sun C:they are faraway from magnetic fields D:they are close to magnetic fields

{{B}}第三篇{{/B}}

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?{{B}}Sunspots{{/B}}
? ?It’s not surprising that sunspots (太阳黑子) were observed by ancient astronomers (天文学家). The largest sunspots on the sun can be seen without a telescope. It was not until the invention of the telescope (望远镜) in the early 17th century, however, that systematic studies of sunspots could be undertaken. The great astronomer Galileo was among the first to make telescopic observations of sunspots.
? ?Sunspots are regions of extremely strong magnetic fields (磁场) found on the sun’s surface. A sunspot has a dark central core known as the umbra. The umbra is surrounded by a dark ring called the penumbra, where the magnetic field, spreads outward. Sunspots appear dark because they are giving off less radiation. They are cooler than the rest of the sun’s surface.
? ?Sunspots are frequently observed in pairs or in paired groups. The members of a spot pair are identified as the leading spot and the following spot. They are identified by their position in the pair in terms of the direction in which the sun rotates (旋转).
? ?The number of sunspots at any one time varies. A large spot group may consist of as many as 10 groups and 300 spots across the sun. The number of spots changes in a fairly regular pattern called the sunspot cycle. The largest number occurs about every 11 years. At sunspot minimum, there are at most just a few small spots.
? ?The average lifetime of an individual spot group is roughly one solar rotation, which is about 25 days. The most persistent large spots, however, can survive for two to three months.
Sunspots are cooler than the rest of the sun’s surface because

A:they produce less energy B:they are buried in the sun C:they are far away from magnetic fields D:they are close to magnetic fields

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