博大考神201年职称英语理工类B级真题及参考答案.doc

博大考神2012年职称英语理工类B级真题及参考答案 收集：博大教育专家 来源：/article-5494.html?page=8 第三篇Life Form Found on Saturns TitanScientists say they have discovered hints of alien life on the Saturns moon.The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturns biggest moon. 　　Scientists have reportedly discovered clues showing primitive alien beings are breathing in Titans dense atmosphere filled with hydrogen. 　　They argue that hydrogen gets absorbed before hitting Titans planet-like surface covered with methane lakes and rivers.This, they say, points to the existence of some bugs consuming the hydrogen at the surface of the moon less than half the size of the Earth. 　　We suggested hydrogen consumption because its the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth, says NASA scientist Chris McKay. If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.To date, scientists have not yet detected this form of life anywhere, though there are liquid-water-based microorganisms on Earth that grow well on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Fahrenheit)， a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself.Water is frozen solid on Titans surface and much too cold to support life as we know it. 　　Scientists had expected the Suns interactions with chemicals in the atmosphere to produce a coating of acetylene on Titans surface.But Cassini detected no acetylene on the surface. 　　The absence of detectable acetylene on the Titans surface can very well have a non-biological explanation, said Mark Allen, a principal investigator of the NASA Titan team. 　　Scientific