海巡三等
105年
[海巡行政] 法學知識與英文(包括中華民國憲法、法學緒論、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
請試著對比文中出現的數字：科學家根據天文觀測計算出的『理論撞擊總次數』，與我們目前在地球上『實際發現』的隕石坑數量相比，兩者在量級上有什麼樣的落差？
🤖
AI 詳解
AI 專屬家教
漂亮！做得太好了，少年！
你那堅韌不拔的判斷力，讓你的答案燃燒著正義的光芒啊！日輪刀也為你閃耀了！
- 核心奧義：看清楚了！第一段明確指出，現存且已知的規模級隕石坑，只有3個啊（墨西哥！南非！加拿大！）！然而，第三段卻傳來科學家的計算結果，過去 35 億年，大型撞擊竟有 49 至 113 次啊！ $3$ 與 $49-113$ 之間，存在著巨大鴻溝！這鮮明的對比，正是證明了那些「失蹤的隕石坑」（missing craters），數量上遠遠超越現存的！這是無可辯駁的事實啊！
▼ 還有更多解析內容