录音原文

Don: Time now for another episode of a Moment of Science. Did you know? So Yael, did you know that there’ve been 23 mass extinctions since life begun on earth.
唐：又到了我们的科学时刻了uyGF+azb%7。耶尔，你知道吗？自从地球出现以来，她已经历了23次大规模的物种灭绝VbirytHUA07JG*o。
Yale: I know there’ve been a few extinctions, Don, but not that many.
耶尔：唐，我知道地球确实经历了几次物种灭绝，但没你说的那么多x(Jyi,-Y]6d4)jJLv。
Don: Yep, many were prehistoric bacteria and other single-cell microorganisms, but in the past 540 million years or so, there’ve been about 5 mass extinctions. Many are marine plants and animals but also off-land organisms.
唐：是的_#bzELIKb6xzW^nljG。远古时候，地球上存在着大量的细菌和其它单细胞的微生物，但在过去的5亿4000万年内，地球经历了5次大灭绝，灭绝的大多是海洋植物和海洋动物，但也有一些陆地生物ekbjyf0RYU4H。
Yale: I know that the dinosaurs disappeared about 65 million years ago possibly due to a large meteor crushing into earth and block out the sun. But what cause all those other extinctions?
耶尔：嗯，我听说恐龙是在大约6千500万年前灭绝的，可能是流星撞击地球之后太阳光被遮挡造成的*S3rkL]vQp^ta9Ou。其它几次灭绝是什么原因？
Don: That’s been a mystery for a long time. But now some scientists think that most mass extinctions have been driven by the rise and fall of sea level. That may sound strange. But consider that millions and millions years ago, a shallow sea covered the entire middle section of North America. That sea grew and shrank back several times. Each time it drained, it caused entire species of sea plants and creatures to die off. The last time it drained was around 65 million years ago when the dinosaurs disappeared.
唐：那是一个埋藏许久的谜团(I)1@nf]=-M,Be^a。但是，现在的一些科学家认为，是海平面的上升或下降造成了这些大灭绝cv@4~ysM!DUw。这听起来可能有点奇怪plwelfCB8xwTv((g,6s。但是，考虑到亿万年前覆盖整个北美大陆中部的只是一层浅海，这片海域几经上升和回落*wbmZX5ixA7XVD。每次干涸，它都会造成整个海洋植物和动物的消亡;SuzZ!^ydTmtSrW3f0d。它的最后一次干涸出现在6千500万年前，正是在那个时候，恐龙彻底灭亡了([F8o|d2SQ+Ppo6。
Yale: OK, I understand that was sea vanishing would kill of the marine life. But did the sea’s disappearing also have something to do with the dinosaurs going extinct?
耶尔：好吧，我知道了海洋消失的确会使海洋生物灭绝，但是也能使恐龙灭绝吗？
Don: Maybe. When the sea disappears, it has big effect on climate. All that water provides heat and moisture. And when the sea drains, the climate becomes drier and colder. So the changing climate may have combine with meteor impact to kill off the dinosaurs.
唐：也许是这样的7[DjKZNi8q。当海洋消失时，会对气候产生巨大影响nzyZookvMhJO。海水可以提供热量和湿气gIFF&KK+B4c2@Zk[7Ed。但是当海洋干涸时，气候会变得干燥和寒冷__%hdg%vZyk|;~B。因此，气候变化和流星撞击地球可能是恐龙灭绝的元凶r3W@6)%(P5YVJ_hC%2。

重点讲解

1. extinction n.熄灭，消灭
例句：His movie of the extinction of dinosaurs was a great success. 他的关于恐龙灭绝的电影取得了巨大的成功,hEt;_O+[uvTVxwEC。
2. prehistoric a.史前的
例句：Prehistoric man used flint knives. 史前人用打火石刀pq]t6N+;%v@&6。
3. marine a. 海的, 海产的
例句：Cultivation of marine organisms in their natural habitats is usually for commercial purposes. 在海洋生物的天然栖息地养殖这些生物，通常是出于商业目的5Ja2CY=s0r3^YzphVO。