According to the research of NCAR, if the concentrations were held steady at 2000 levels,

A:the ocean's capacity to absorb heat would decline. B:the sea-level would keep on increasing. C:the global average temperature would decrease. D:significant climate change would not take place.

It seems to shine unchangingly, pouring out a constant light year after year. But the sun may not be nearly so stable as we suppose, It is now thought to move quickly and irregularly and change in long-term cycles, growing dimmer and then brighter with each passing year. Some even fear that its frequent changing behavior would have a great influence on the Earth’s climate.
The source of the sun’s inconstancy is magnetism. Professor William Livingston has developed new theories about its magnetic nature.
"We don’t yet know what causes sun spots, "he says, "but we now think they’re areas of high-level magnetism that come up from the sun’s interior. So strong is their magnetic pull that the highly ionized gas nearby is not able to transmit energy out." As a result these areas send out less heat and light and thus appear from Earth to be almost dark irregular surface patches.
Sun spot activity generally fluctuates in steady, 11-year cycled. Scientists have long formed the opinion that as the size and number of sun spots increased, the overall energy sent out by the sun would decrease. Indeed, recent studies confirmed it, revealing that during peak periods of sun spot activity, the Earth experiences a small drop that can be seen clearly in received solar energy.
Could such a small drop in energy have an effect here on earth Perhaps some scientists think the world temperature could fall by as much as 0.2 during periods of high solar magnetism... enough to cause significant fluctuations in weather patterns.
According to the passage, it is believed that the sun ______ .

A:moves in a quick but steady way year after year B:sends out less and less heat and light with each passing year C:radiates the same amount of light every year D:might have a strong influence on the weather patterns

Passage 2
It seems to shine unchangingly, pouring out a constant light year after year. But the sun may not be nearly so stable as we suppose. It is now thought to move quickly and irregularly and change in long-term cycles, growing dimmer and then brighter with each passing year. Some even fear that its frequent changing behavior would have a great influence on the Earth’ s climate.
The source of the sun’ s inconstancy is magnetism. Professor William Livingston has developed new theories about its magnetic nature.
"We don’ t yet know what causes sun spots, "he says, "but we now think they ’ re areas of high level magnetism that come up from the sun’ s interior. So strong is their magnetic pull that the highly ionized gas nearby is not able to transmit energy out. "As a result these areas send out less heat and light and thus appear from Earth to be almost dark irregular surface patches.
Sun spot activity generally fluctuates in steady, 11-year cycled. Scientists have long formed the o pinion that as the size and number of sun spots increased, the overall energy sent out by the sun would de crease. Indeed, recent studies confirmed it, revealing that during peak periods of sun spot activity, the Earth experiences a small drop that can be seen clearly in received solar energy.
Could such a small drop in energy have an effect here on earth Perhaps some scientists think the world temperature could fall by’ as much as 0.2 during periods of high solar magnetism.., enough to cause significant fluctuations in weather patterns.

According to the passage, it is believed that the sun （）

A:moves in a quick but steady way year after year B:sends out less and less heat and light with each passing year C:radiates the same amount of light every year D:might have a strong influence on the weather patterns

Passage Two

According to the passage, it is believed that the sun ______ .

A:moves in a quick but steady way year after year B:sends out less and less heat and light with each passing year C:radiates the same amount of light every year D:might have a strong influence on the weather patterns

Volcanic fire and glacial ice are natural enemies. Eruptions at glaciated volcanoes typically destroy ice fields, as they did in 1980 when 70 percent of Mount Saint Helens ice cover was de molished. During long dormant intervals, glaciers gain the upper hand cutting deeply into volcanic cones and eventually reducing them to rubble. Only rarely do these competing forces of heat and cold operate in perfect balance to create phenomenon such as the steam caves at Mount Rainier Park.
Located inside Rainier’s two ice-filled summit craters, these caves form a labyrinth of tunnels and vaulted chambers about one and one-half miles in total length. Their creation depends on an unusual combination of factors that nature almost never brings together in one place. The cave-making recipe calls for a steady emission of volcanic gas and heat, a heavy annual snowfall at an elevation high enough to keep it from melting during the summer, and a bowl-shaped crater to hold the snow.
Snow accumulating yearly in Rainier’s summit craters is compacted and compressed into a dense form of ice called firn, a substance midway between ordinary ice and the denser crystalline ice that makes up glaciers. Heat rising from numerous openings (called fumaroles) along the inner crater walls melts out chambers between the rocky walls and the overlying ice pack. Circulating currents of warm air then melt additional opening in the firn ice, eventually connecting the individual chambers and, in the larger of Rainier’s two craters, forming a continuous passageway that extends two-thirds of the way around the crater’ s interior.
To maintain the cave system, the elements of fire under ice must remain in equilibrium, Enough snow must fill the crater each year to replace that melted from below. If too much volcanic heat is discharged, the crater’ s ice pack will melt away entirely and the caves will vanish along with the snows of yesteryear. If too little heat is produced, the ice replenished annually by winter snowstorms will expand, pushing against the enclosing crater wails and smothering the present caverns in solid firn ice.

The second paragraph mentions all of the following as necessary elements in the creation of steam caves EXCEPT （　）

A:a glacier B:a crater C:heat D:snow

{{B}}第三篇{{/B}}

The second paragraph mentions all of the following as necessary elements in the creation of steam caves EXCEPT ______.

A:a glacier B:a crater C:heat D:snow

Many scientists today are convinced that life exists elsewhere in the universe-life probably much like that on our own planet. They reason in the following way.
As far as astronomers can determine, the entire universe is built of the same matter. They have no reason to doubt that matter obeys the same laws in every part of the universe. Therefore, it is reasonable to guess that other stars, with their own planets, were born in the same way as our own solar system. What we know of life on earth suggests that life will arise wherever the proper conditions exist.
Life requires the right amount and kind of atmosphere. This eliminates all those planets in the universe that are not about the same size and weight as the earth. A smaller planet would lose its atmosphere; a larger one would hold too much of it.
Life also requires a steady supply of heat and light. This eliminates double stars, or stars that flare up suddenly. Only single stars that are steady sources of heat and light like our sun would qualify.
Finally, life could evolve only if the planet is just the right distance from its sun. With a weaker sun than our own, the planet would have to be closer to it. With a stronger sun, it would have to be farther away.
If we suppose that every star in the universe has a family of planets, then how many planets might support life First, eliminate those stars that are not like our sun. Next eliminate most of their planets; they are either too far from or too close to their suns. Then eliminate all those planets which are not the same size and weight as the earth. Finally, remember that the proper conditions do not necessarily mean that life actually does exist on a planet. It may not have begun yet, or it may have already died out.
This process of elimination seems to leave very few planets on which earthlike life might be found. However, even if life could exist on only one planet in a million, there are so many billions of planets that this would still leave a vast number on which life could exist.
The existence of life depends on all of the following factors EXCEPF ______.

A:the right amount of atmosphere B:our own solar system C:steady heat and light D:the right distance from the sun

Many scientists today are convinced that life exists elsewhere in the universe-life probably much like that on our own planet. They reason in the following way.
As far as astronomers can determine, the entire universe is built of the same matter. They have no reason to doubt that matter obeys the same laws in every part of the universe. Therefore, it is reasonable to guess that other stars, with their own planets, were born in the same way as our own solar system. What we know of life on earth suggests that life will arise wherever the proper conditions exist.
Life requires the right amount and kind of atmosphere. This eliminates all those planets in the universe that are not about the same size and weight as the earth. A smaller planet would lose its atmosphere; a larger one would hold too much of it.
Life also requires a steady supply of heat and light. This eliminates double stars, or stars that flare up suddenly. Only single stars that are steady sources of heat and light like our sun would qualify.
Finally, life could evolve only if the planet is just the right distance from its sun. With a weaker sun than our own, the planet would have to be closer to it. With a stronger sun, it would have to be farther away.
If we suppose that every star in the universe has a family of planets, then how many planets might support life First, eliminate those stars that are not like our sun. Next eliminate most of their planets; they are either too far from or too close to their suns. Then eliminate all those planets which are not the same size and weight as the earth. Finally, remember that the proper conditions do not necessarily mean that life actually does exist on a planet. It may not have begun yet, or it may have already died out.
This process of elimination seems to leave very few planets on which earthlike life might be found. However, even if life could exist on only one planet in a million, there are so many billions of planets that this would still leave a vast number on which life could exist.
Which of the following statements is INCORRECT

A:The planet must be as big and heavy as the earth. B:Proper conditions are essential to the existence of life. C:Double stars can provide steady light and heat. D:The distance between a planet and its sun should be right.