Life Form Found on Saturns Titan　　Scientists say they have discovered hints of alien life1 on the Saturns moon2. The discovery of a sort of life was announced after researchers at the US space agency,NASA3,analyzed data from spacecraft Cassini4,which pointed to,the existence of methane-based form of life on Saturns biggest moon.　　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 somebugs5 consuming the hydrogen at the surface of the moon less than half the size of the 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 Kelvin6,a methanebased 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.　　The absence of detectable acetylene on the Titans surface can very well have a non-biological explanation,said Mark Allen,a principal investigator7 of the NASA Titan team.　　詞匯：　　methane n.甲烷，沼氣　　acetylene n.乙炔　　conservatism n.保守主義,守舊　　1.hints of alien life：外星生命跡象。　　3.NASA：美國國家航空航天局的縮寫，全稱是： National Aeronautics and Space Administration。　　5.bugs：微生物。非正式口語表達，所以使用了引號。　　7.principal investigator：研究項目負責人　　練習：　　A They have found a new moon orbiting Saturn.　　C They have found methane-based life on Titan.　　2. What do scientists say about Titan?　　B There is acetylene there.　　D Rivers and lakes there contain life formls.　　A Water-based life.　　C Liquid-water-based microorganisms.　　4. What can be inferred from what Allen said?　　B Scientists all agree that there is life on Titan.　　D Scientists all agree that a non-biological chemical reaction is a possible explanation.　　A Earthlike Living Beings Found on Titan.　　C Titan,a New Satellite Found.　　答案與題解：　　2.A根據第二段Scientists have reportedly discovered clues showing primitive alien beings are breathing in Titans dense atmosphere filled with hydrogen.，說明土衛六有生命跡象。因此A是答案。　　4.A科學家至今對土衛六是否存在生物有不同的觀點和解釋。Allen 說要做出土衛六上有生　　5.D該短文的主題是，科學家在土衛六上發現了一種與地球生物不同的生命形式的跡象，即以甲烷為生命基礎呼吸氫氣的生物，但科學家還未能最后驗證這一發現。第四段中的一個句子能夠揭示該短文的主題：If these signs do turn out to be a sign of life, it would bedoubly exciting because it would represent a second form of life independent from water-based life on Earth.

　　Life Form Found on Saturns Titan　　Scientists say they have discovered hints of alien life1 on the Saturns moon2. The discovery of a sort of life was announced after researchers at the US space agency,NASA3,analyzed data from spacecraft Cassini4,which pointed to,the existence of methane-based form of life on Saturns biggest moon.　　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 somebugs5 consuming the hydrogen at the surface of the moon less than half the size of the 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 Kelvin6,a methanebased 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.　　The absence of detectable acetylene on the Titans surface can very well have a non-biological explanation,said Mark Allen,a principal investigator7 of the NASA Titan team.　　詞匯：　　methane n.甲烷，沼氣　　acetylene n.乙炔　　conservatism n.保守主義,守舊　　1.hints of alien life：外星生命跡象。　　3.NASA：美國國家航空航天局的縮寫，全稱是： National Aeronautics and Space Administration。　　5.bugs：微生物。非正式口語表達，所以使用了引號。　　7.principal investigator：研究項目負責人　　練習：　　A They have found a new moon orbiting Saturn.　　C They have found methane-based life on Titan.　　2. What do scientists say about Titan?　　B There is acetylene there.　　D Rivers and lakes there contain life formls.　　A Water-based life.　　C Liquid-water-based microorganisms.　　4. What can be inferred from what Allen said?　　B Scientists all agree that there is life on Titan.　　D Scientists all agree that a non-biological chemical reaction is a possible explanation.　　A Earthlike Living Beings Found on Titan.　　C Titan,a New Satellite Found.　　答案與題解：　　2.A根據第二段Scientists have reportedly discovered clues showing primitive alien beings are breathing in Titans dense atmosphere filled with hydrogen.，說明土衛六有生命跡象。因此A是答案。　　4.A科學家至今對土衛六是否存在生物有不同的觀點和解釋。Allen 說要做出土衛六上有生　　5.D該短文的主題是，科學家在土衛六上發現了一種與地球生物不同的生命形式的跡象，即以甲烷為生命基礎呼吸氫氣的生物，但科學家還未能最后驗證這一發現。第四段中的一個句子能夠揭示該短文的主題：If these signs do turn out to be a sign of life, it would bedoubly exciting because it would represent a second form of life independent from water-based life on Earth.