問題詳情

V. Reading Comprehension（5%）Exploding fireworks are beautiful, but nature’s fireworks─exploding volcanoes─are very frightening! When magma (岩漿), the red-hot liquid rock found inside the earth, starts moving upward, it puts great pressure on the ground, causing earthquakes and pushing the earth’s surface. If it pushes hard enough, it bursts through as a volcano.Thick magma explodes strongly at high temperatures of 1000 to 1250℃, throwing burning rocks, ash, and gases all around. Once magma is above the ground, it is called “ lava.” Lava affects all life forms. For instance, when Mount St. Helens, U.S.A., erupted (爆發) in 1980, volcanic ash and gases killed everything in the 200-square-mile area around it. Fifty-seven scientists and officials keeping a watch on the volcano died, along with 24,000 animals in the nearby forest. According to the U.S. Geological Survey, enough wood to build 300,000 houses was also destroyed. In Spokane, a city 250 miles away from the volcano, ash darkened the sky and caused people to have breathing difficulties. Fortunately, only few people living in the area died, as scientists studying the volcano had given warnings weeks in advance.In spite of such destruction, volcanoes can be useful. Their lava forms productive soil, which is excellent for farming. As for those living near volcanoes, they can depend on geologists who use different devices to predict eruptions and issue warnings to let people leave unsafe zones. Therefore, studying volcanoes and understanding their activity turns them into valuable natural resources we can appreciate, not merely disasters we fear.
56. Before lava comes out of the ground, it is called ______.
(A) ash
(B) gases
(C) magma
(D) volcano

參考答案

答案：C
難度：適中0.538462
統計：A(0),B(1),C(7),D(3),E(0)

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