填空题
1 [■] The Earth is very dynamic and complex processes often result in unusual formations. 2 [■] Volcanoes form deep within the bowels of the earth in places, where hot sticky magma tries to push its way outward to the surface. 3 [■] The earth starts to rumble and grumble as thinned magma called lava makes its way to the top of the mantle. 4 [■] The magma collects slowly in places called hot spots and starts putting pressure on the upper crust. 1 [□] These tiny fissures allow lava to leak out slowly and pour down the side of the volcano. 2 [□] A billow of noxious gas and ash accompanies the phenomenon. 3 [□] When the inner pressure becomes unbearable, a volcanic eruption takes place. 4 [□] Lava bursts forth in one gigantic explosion burying everything in its path.
These explosions are normal occurrences in the geology of the earth. 1 [■] Volcanologists, however, have come up with evidence of more unusual volcanic activity than the one witnessed thus far. 2 [■] New sites uncovered in Yellowstone National Park and Long Valley, California, demonstrate the existence of so-called super volcanoes. 3 [■] These super volcanoes would have had erupted some 750,000 years ago and completely altered the surrounding landscape around over a distance of several hundred thousand feet. 4 [■] Geologists are certain that super volcanoes are currently in a state of dormancy. 1 [□] They can erupt sometime in the distant future, once they become active again. 2[□] It is possible that the next super volcanic eruption will occur at the end of our millennium. 3 [□] While we may not be alive by then to witness it, uncovering clues as to how these fantastic activities take place should make predicting them easier. 4 [□]
Super volcanoes form beneath so-called hot spots within the earth"s mantle. 1 [■] When two tectonic plates move one beneath the other, the earth mantle melts to form a viscous flow-resistant substance. 2 [■] This substance, the magma, slowly accumulates inside a magma chamber and heats up the earth crust above. 3 [■] This newly formed magma exerts formidable pressure on the soil, as it does not allow any water or gas to leak out. 4 [■] The earth cracks along a vertical line and finally lava explodes to the surface. 1 [□] A Super volcanic eruption is more of an outburst of cataclysmic proportion. 2 [□] when the lava bursts forth, a pyroclastic flow of scalding ash and gas accompanies the explosion. 3 [□] The rocks above the magma chamber collapse under the pressure to make room for a dome shaped crater called a caldera. 4 [□] Over time, more magma collects under the caldera and fresh lava may leak out the sides. But it is not until sufficient magma accumulates inside the chamber that a new super volcano erupts again.
Climatologists have documented the devastating effects of super volcanic eruptions for mankind. 1 [■] One such effect would be the sheer size of land covered by lava. 2 [■] The lava that exists in a volcano didn"t have any time to leak out before the actual explosion. 3 [■] Thus, it has a larger volume when spewed out, which means it may cover a territory twice as big as the state of California alone. 4 [■] These gases that result from a super volcanic eruption have high sulfate content. This sulfate binds with ozone to form sulfuric acid. 1 [□] Therefore, the world"s atmosphere gets depleted of the vital ozone that usually protects us from harmful UV rays. 2 [□] The ozone hole would only get bigger in the event of a super volcano. 3 [□] The sulfuric acid that would accumulate in the atmosphere would eventually condense and poison the environment while falling down on earth. 4 [□]

lava: magma rock that has erupted from a volcano or fissure and flowed on to the Earth"s surface or the ocean, floor
tectonic plates: a small number of large plates of solid rock, whose movements m relation to each other are responsible for continental drift
pyroclastic: of an individual fragment of lava that has been ejected into the atmosphere during a volcanic eruption

填空题 Look at the four squares in paragraph 1 that indicate where the following sentence could be added to the passage.
One such formation is for instance a super volcano.
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填空题 Look at the four squares in paragraph 1 that indicate where the following sentence could be added to the passage.
As a result of this pressurized force, the soil begins to crack to make room for the magma to come out.
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填空题 Look at the four squares in paragraph 2 that indicate where the following sentence could be added to the passage.
They wreak havoc, but are expected to happen.
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填空题 Look at the four squares in paragraph 2 that indicate where the following sentence could be added to the passage.
That means they are in a temporary state of sleep.
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填空题 Look at the four squares in paragraph 3 that indicate where the following sentence could be added to the passage.
These spots or places are usually located in subduction zones.
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填空题 Look at the four squares in paragraph 3 that indicate where the following sentence could be added to the passage.
Unlike in normal volcanic eruptions, this explosion does not slowly die out.
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填空题 Look at the four squares in paragraph 4 that indicate where the following sentence could be added to the passage.
Moreover, the gases that accompany the lava flow are extremely toxic.
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填空题 Look at the four squares in paragraph 4 that indicate where the following sentence could be added to the passage.
Another negative outcome of a super volcanic eruption is the resulting acid rain.
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