The binary planet hypothesis—that Earth and the Moon formed simultaneously by the accretion of smaller objects—does not explain

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问题 The binary planet hypothesis—that Earth and the Moon formed simultaneously by the accretion of smaller objects—does not explain why the Moons iron core is so small relative to the Moons total volume, compared with Earth’s core relative to Earths total volume. According to the giant-impact hypothesis, the Moon was created during a collision between Earth and a large object about the size of Mars. Computer simulations of this impact show that both of the objects would melt in the impact and the dense core of the impactor would fall as molten rock into the liquefied iron core of Earth. The ejected matter—mantle rock that had surrounded the cores of both objects—would be almost devoid of iron. This matter would become the Moon.
The giant-impact hypothesis as described in the passage answers all of the following questions EXCEPT:

选项 A、What happened to the rock that surrounded the impactor s core after the impactor hit Earth?
B、What happened to the impactor s core after the impactor hit Earth?
C、Where did the impactor that collided with Earth originate?
D、Why is the Moons iron core small relative to that of Earth?
E、What was the size of the impactor relative to that of Mars?

答案B

解析 The questions in Choices A, B, D, and E are all answered by the giant-impact hypothesis: for Choice A, the rock that surrounded the impactor s core "would become the Moon"; for Choice B, the impactor s core "would fall as molten rock into the liquefied iron core of the Earth"; for Choice D, the Moons iron core is small relative to the Earth’s core because the matter that formed the Moon was "almost devoid of iron"; and for Choice E, the passage states that the impactor was "a large object about the size of Mars." But nothing in the passage refers to the origin of the impactor, so Choice B is the correct answer.
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本试题收录于: GRE VERBAL题库GRE分类
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