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  3. Earth Rocks on Most of the time, the ground feels solid beneath our feet. That’s comforting. But it’s also misleading becaus

Earth Rocks on Most of the time, the ground feels solid beneath our feet. That’s comforting. But it’s also misleading becaus

admin2011-04-18  5
问题                      Earth Rocks on
    Most of the time, the ground feels solid beneath our feet. That’s comforting. But it’s also misleading because there’s actually a lot going on underground. Masses of land (called plates) slip, slide, and bump against one another, slowly changing each other, slowly changing the shape of continents and oceans over millions and billions of years.
    Scientists know that Earth formed about 4. 5 billion years ago. They also know that our planet was hot at first. As it cooled, its outermost layer, called the crust (地壳) , eventually formed moving plates. Exactly when this shift happened, however, is an open question.
    Now, an international group of researchers has an answer. They’ve found new evidence suggesting that Earth’s crust started shifting at least 3. 8 billion years ago. The new estimate is 1. 3 billion years earlier than previous ones.
    Not long before 3. 8 billions years ago, lots of asteroids (小行星) were hitting Earth, keeping its crust in a hot, melted state. After the hard crust formed, much of it sank at various times into the planet’s hot insides. There, it melted before returning to the surface. In some places, however, the crust never sank. One of the oldest such places is in Greenland, in an area called the Isua Supra-crustal (上地壳) Belt. The rocky crust there is between 3. 7 and 3. 8 billion years old. The belt was once part of the seafloor, but now it is exposed to air.
    The researchers recently took a close look at the Isua supracrustal belt. They noticed long, parallel cracks in the rock that have been filled in with a type of volcanic rock.
    To explain this structure, the scientists proposed that tension in the crust caused the seafloor to crack open long ago. Hot, liquid rock, called magma (岩浆) , flowed up slowly from deep inside Earth to fill the cracks. Finally, the whole area cooled, forming what we see today.
    That explanation, plus chemical clues inside the rock, suggests that the Isua supracrustal belt was once part of a plate under the ocean, beginning around 3. 8 billion years ago.  
The shape of lands and oceans changed as the plates bumped in to each other.
选项 A、Right
B、Wrong
C、Not mentioned
答案A
解析 本题给出的信息是正确的，文章在第一段中提到“Masses of land(called plates)slip，slide，and bump against one another，slowly changing each other，slowly changing the shape of continents and oceans over millions and billions of years．”大片的陆地(被称作板块)在亿万年中发生着快速的滑动、缓慢的滑动，甚至是撞击，渐渐改变陆地和海洋的形状。说明题目中陈述的海洋和陆地的形状会随着板块的相互撞击而改变这一说法，是符合原文意思的。
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本试题收录于： 职称英语理工类A级题库职称英语分类
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