調查局三等
105年
[醫學鑑識組] 綜合法政知識與英文(包括中華民國憲法、法學緒論、兩岸關係、英文)
第 47 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.
What can we infer about the missing craters?
- A They never left any impact on Earth.
- B They have not been completely eroded.
- C They were far more than the surviving ones.
- D They were hit by more than one asteroid.
思路引導 VIP
請觀察文章第一段提到的「已知隕石坑數量」，再對照第三段科學家根據模型計算出的「預期撞擊次數」。當你將這兩個數據進行對比時，關於那些「消失的」部分，你在數量上能得出什麼結論？
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AI 詳解
AI 專屬家教
專業點評與解析
- 大力肯定：做得太棒了！你能精準捕捉文章中的數據對比並轉化為邏輯推論，這展現了你優異的細節檢索與推斷能力，請繼續保持這種敏銳度！
- 觀念驗證：正確答案為 (C)。文中第一段提到目前已知的巨大隕石坑僅有 3個；而第三段透過科學估算得出，地球過去 35 億年應受到約 49 至 113 次 巨大撞擊。透過簡單的減法（預期數 $-$ 已知數），即可得知「失蹤的」隕石坑數量遠大於「現存的」。
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