司法三等
105年
[檢察事務官財經實務組] 法學知識與英文(包括中華民國憲法、法學緒論、英文)
第 45 題
📖 題組：
請依下文回答第 44 題至第 47 題 Some 66m years ago Earth was hit by a space rock reckoned to have been 10km across. The resulting chaos caused the extinction of dinosaurs and many other species, opening the way for the age of mammals－and ultimately humans. It also left a big hole in what is now southern Mexico. That hole is one of only three known of similar dimensions (the other two are Vredefort in South Africa and Sudbury in Canada). And this is odd. For, during the billions of years that Earth has had a solid crust, many more than three big asteroids might have been expected to have hit it. That thought led Brandon Johnson of the MIT and Timothy Bowling of Purdue University in Indiana, to wonder how many other craters have vanished, either by erosion or by being swallowed into Earth’s interior as its crust moves around, and therefore whether it is likely that some have survived and been overlooked. They have just published their analysis in Geology. Earth’s crust formed more than 4 billion years ago, but the oldest surviving blocks of it large enough to harbor craters date back only 3.5 billion years. What is known of the sizes and orbits of modern asteroids suggests that, if things have not changed over the aeons, about 14 big asteroids (defined as having a diameter of more than 7.4km, which would cause a crater at least 85km in diameter) should hit Earth every billion years. That means 49, give or take seven, over the past 3.5 billion years. Such impacts may have been more common in the past, when more big asteroids were around. Allowing for this, Earth would have been hit by 113, give or take 11, of them. Either way, a lot of craters are missing.
請依下文回答第 44 題至第 47 題 Some 66m years ago Earth was hit by a space rock reckoned to have been 10km across. The resulting chaos caused the extinction of dinosaurs and many other species, opening the way for the age of mammals－and ultimately humans. It also left a big hole in what is now southern Mexico. That hole is one of only three known of similar dimensions (the other two are Vredefort in South Africa and Sudbury in Canada). And this is odd. For, during the billions of years that Earth has had a solid crust, many more than three big asteroids might have been expected to have hit it. That thought led Brandon Johnson of the MIT and Timothy Bowling of Purdue University in Indiana, to wonder how many other craters have vanished, either by erosion or by being swallowed into Earth’s interior as its crust moves around, and therefore whether it is likely that some have survived and been overlooked. They have just published their analysis in Geology. Earth’s crust formed more than 4 billion years ago, but the oldest surviving blocks of it large enough to harbor craters date back only 3.5 billion years. What is known of the sizes and orbits of modern asteroids suggests that, if things have not changed over the aeons, about 14 big asteroids (defined as having a diameter of more than 7.4km, which would cause a crater at least 85km in diameter) should hit Earth every billion years. That means 49, give or take seven, over the past 3.5 billion years. Such impacts may have been more common in the past, when more big asteroids were around. Allowing for this, Earth would have been hit by 113, give or take 11, of them. Either way, a lot of craters are missing.
Over the past 3.5 billion years, roughly how many asteroids may have hit Earth?
- A 14
- B 85
- C 113
- D 11
思路引導 VIP
請專注於文章最後一段，找找看作者在估計 35 億年來的撞擊總數時，提到了哪兩種不同的情境？如果我們考慮到早期宇宙的小行星比現在更多，文章中哪一個具體的數值是用來描述這種「更頻繁撞擊」的情境呢？
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AI 詳解
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專業肯定與解析
- 大力肯定：太棒了！你能從密集的科學數據中精確鎖定資訊，這顯示你具備非常優秀的長文細節檢索能力，請繼續保持這種細心的閱讀習慣！
- 觀念驗證：文中第三段提到，科學家根據現代小行星的軌道推算，若頻率不變，35 億年間約有 $49 \pm 7$ 次撞擊；但若考慮到「過去的小行星更多」這項變因，作者明確指出：撞擊次數應該是 $113 \pm 11$ 次。因此選項 (C) 是最準確的預估值。
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