【正文】 t rule out the existence of a biological munity down there then these factors certainly would, or so they thought. Student 2 So you are telling us they did find anisms that could live under those conditions? Professor: They did indeed, something like 300 different species Student 1 But... but how could that be? I mean without sunlight, no energy, no no … Protessor: What they discovered was that microanisms, bacteria, had taken over both functions of the biological munity the recycling of waste materials and the production of energy. They were the energy source. You see, it turns out that certain microanisms are chemosynthetic they don39。t rea ch that far down so it ’ s totally dark. There couldn ’ t be any plant or animal life since there39。 texts and drawings through the medieval over w riting . Lecture 4 Narrator: Listen to part of a lecture in a biology class. Professor: OK. We39。t be deciphered, this technique39。ve used ultraviolet light and some other techniques, and if you39。 text was erased and written over, and no one knew it existed. It wasn39。s considered one of the greatest Mathematicians who ever lived, even though , many of his writings had been lost , includi ng what many now think to be his most important work called The Method . But in 1998, a book of prayers from the Middle Ages sold in an art auction for a lot of money, more money than anyone would pay for a damaged book from the 12th century. Beautiful or not, why? It had been discovered that the book was a palimpsest, and beneath the surface writing on the manual script laid, guess what? Mathematical theorems and diagrams from Archimedes Archimedes39。d perform in your races? Lecture 3 Narrator: Listen to part of a lecture in an art history class . Professor: Now in Europe in the Middle Ages before the invention of printing and the p r inting pres s, all books, all manual scripts were handmade. And the material typically used for the pages was parchment, which is animal skin that stretched and dried under tension, so it bec o me s really fat and can be written on . During the 1400s, when printing was being developed, paper became the predominant material for books in Europe, but prior to t hat, it was parchment . Parchment is durable, much more so than paper, and it could be reus ed which came in handy since it was a costly material and in short supply. So it wasn ’ t unmon for the scribes or monks who produce the manual scripts . Ah, remember before printing books were made mainly in monasteries . Well, the scribes often recycled the parchment that ’ d been used for earlier manual scripts. They simply erased the ink off the parchment and wrote something new in its place A manual script page that was written on, erased and then used again is called a palimpsest . Palimpsests were created, well, w e kn ow about two methods that were used for removing ink from parchment. In the late Middle Ages, it was customary to scrape away the surface of the parchment with an abrasive, which pletely wiped out any writing that was there. But earlier in the Middle Ages, the original ink was usually removed by washing the used parchment with milk. That removed the ink. But with the passing of time, the original writing might reappear. In fact , it might rea pp ear to the extent that scholars could make out an even deci p her , the original text. Perhaps, the most famous example is the Archimedes39。t realize . Professor Think of your brain as: a muscle. If you didn39。s ability to absorb information starts to decline after about the first hour. So if you are dealing with a lot of new concepts and vocabulary, anyway, if you just reviewed your notes, even 20 minutes a day, it39。s back up. You say you studied, where, at home? Samantha At my kitchen table actually . Professor And that39。t think you could have done that if you hadn39。ll be future researchers who have a better perspective and will be able to really draw a line between the Holocene and the Anthropocene epics. Conversation 2 Narrator Listen to part of a conversation between a student and her biology . Professor Hi Samantha, how did your track meet go? Samantha Great! I placed first in one race and third in another. Professor Congratulations ! You must practice a lot. Samantha Three times a week preseason, but now that we ’ re peting every weekend, we practice 6 days a week from 3:30 till 5:00. Professor Athletics place a heavy demand on your time, don ’ t they? Samantha Yeah, but I really love peting, so … Professor You know I played soccer in college and my biggest challenge, and I didn ’ t always succeed