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火星上有没有水？ 这个问题对于普罗大众来讲或许并不足够引人注目，但对于正在托福备考路上挣扎的同学们来讲一定有一层特殊的意味，因为TPO中阅读和听力都有多篇文章对此有探讨（没有印象的同学说明你的level还不够哇）。
小编找到两个本次事件的视频，其中第一个制作精良短小精悍，听起来更像SSS，而第二个老头的措辞语速等无一不像lecture，拿出来分享给大家，被天文学听力虐残的同学们赶紧过来练习一下！ 制作精良，语速相对较快；在内容上和TPO8-3的阅读有些关联，可以放在一起拓展一下； 老头不紧不慢，俨然TPO中lecture教授的风格，同时表达很地道，非常建议仔细多听到不看字幕能把握到每个细节。
话不多说，直接上图---- 点击看大图 顺便和大家分享一下本篇中一个比较有意思的长难句：
本句最大的亮点在 should have done 这个结构，表示 “本应该做而事实上没有做”，对这个语法点的理解直接影响到对于本篇第十题的解答。
 Professor There’sbeen a lot of talk recently about life on Mars, at the level of microorganismsanyway, mainly because of a few important discoveries and inventions. Forexample, one major discovery was that at one point water was present on Mars.How do we know? Well, in 2004, an exploration robot discovered jarosite there. Jarositeis a yellowish brown xmineral with a crystalline structure that’s also found onEarth. It contains iron, potassium and hydroxide. The interesting thing is thaton Earth at least it needs highly acidic water to form. So we’ve got water orhad it at one point. And since most planetary scientists believe that water isessential to life, the presence of jarosite means that one prerequisite forlife was once present on Mars. Butthere’s another thing about jarosite. One step in its formation on Earthinvolves microorganisms; they actually speed up the formation of jarositedramatically. Now, theoretically it is possible for jarosite to form withoutthe help of biological life forms. But we don’t really know for sure if thishappens ‘cause… well, because every corner of Earth has some form of biologicallife. Butjarosite on Earth incorporates all kinds of microorganisms into its crystallinestructure. So it’s possible that if the jarosite on Mars was also formed withthe help of microorganisms, we might be able to detect remnants of them in thesamples we find. And we have instruments now that will enable us to try to dothis. For example, there’s a new instrument called the microfabricated organicanalyzer, or M.O.A. Theorganic analyzer is an amazing tool. It will be able to collect soil samplesand analyze them right there on Mars, pure, untouched samples. It will let useliminate the risk we would take of contaminating the samples if they werebrought back to Earth. And what they’ll look for specifically in the soil is amino acids. Aminoacids, as you may know, are the building blocks of proteins. In fact, there aretwenty standard amino acids involved in making proteins and lots more thataren’t. Andhere’s the important thing. Amino acids are what we call handed. They can existin two forms, which are mirror images of each other like hands. Right and lefthands have the same number of fingers in the same order plus one thumb. Butright and left hands are not the same; they are mirror images. Well, likehands, amino acids can be right or left-handed. And the twenty that make up theproteins on Earth are all left-handed. Now, onereason the M.O.A., the organic analyzer is so impressive is that it tests notjust for the presence of amino acids but also for the handedness of aminoacids. If amino acids are found, it would be especially interesting if theyshow a prevalence of one type of handedness, either left, like amino acids onEarth, or right. See,other physical processes in space, processes that don’t involve livingorganisms, can create amino acids. But the ones synthesized through abioticprocesses, which is to say not involving microorganisms, occur in equal numbersof right- and left-handed. So, aprevalence of left-handed amino acids would indicate they were biological inorigin, which would be amazing! A prevalence of right-handed ones…well, thatwould be really amazing!! Because the organisms that created them would beunlike anything we have on Earth, which produce only left-handed ones. 更多精品学术文章： 考试日报推荐：
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