阅读理解：According to astronomer S.A.Phinney, kicking a rock hard enough to free it from Earth's gravity would require a meteorite capable of making a crater more than 60 miles across. Moreover, even if Earth rocks were freed by meteorite impact, Mars's orbit is much larger than Earth's, so Phinney estimates that the probability of these rocks hitting Mars is about one-tenth as great as that of Mars's rocks hitting Earth. To demonstrate this estimate, Phinney used a computer to calculate where 1,000 hypothetical particles would go if ejected from Earth in random directions. He found that 17 of the 1,000 particles would hit Mars. 1.Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars? A Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into spacE. B Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year. C No rocks of Earth origin have been detected on Mars. D The velocity of rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth. E No craters more than 60 miles across have been found on Mars.
A.A.B. Moreover, C. To D. He E. 1.Which F. B G. C H. D I. E
【参考答案】
A 文段不长，但谈的细节不少，注意题目问的是哪一个选项可以质疑地球发射的石头击中火星的概率。 根据句3我......