考满分 toefl

1 .Listen to part of a lecture in an astronomy class.

听一段天文学课程上的演讲

1 .There's been a lot of talk recently about life on Mars, at the level of microorganisms anyway, mainly because of a few important discoveries and inventions.

最近有很多关于火星上的生命的话题，虽然仅仅还是在微生物的层面上，主要是因为一些重要的发现和发明。

1 .For example, one major discovery was that at one point water was present on Mars.

举个例子，一个主要的发现是，在火星上曾一度有水存在。

2 .How do we know?

我们怎么知道？

3 .Well, in 2004, an exploration robot discovered jarosite there.

好吧，2004年，一个探索机器人发现黄钾铁矾。

1 .Jarosite is a yellowish brown mineral with a crystalline structure that's also found on Earth.

黄钾铁矾是具有晶体结构的黄棕色矿物，在地球上也发现了这种物质。

2 .It contains iron, potassium and hydroxide.

它含有铁、钾和氢氧化。

3 .The interesting thing is that on Earth at least it needs highly acidic water to form.

有趣的是，在地球上形成它至少需要高酸性水。

4 .So we've got water or had it at one point.

所以我们认为那儿有或者曾经一度有水。

5 .And since most planetary scientists believe that water is essential to life, the presence of jarosite means that one prerequisite for life was once present on Mars.

因为大多数行星科学家认为，水对生命是必不可少的，黄钾铁矾的存在意味着一个生命曾经存在火星上。

1 .But there's another thing about jarosite.

但是还有一件事是关于黄钾铁矾的

2 .One step in its formation on Earth involves microorganisms.

在地球上的形成有一个步骤是需要微生物；

3 .They actually speed up the formation of jarosite dramatically.

他们实际上大大加快黄钾铁矾的形成。

4 .Now, theoretically it is possible for jarosite to form without the help of biological life forms.

。现在，在理论上没有微生物的帮助，黄钾铁矾形成生命是可能的。

5 .But we don't really know for sure if this happens cause... well, because every corner of Earth has some form of biological life.

但是我们真的不知道这种情况发生是否会发生。。。嗯，因为地球的每一个角落都有某种形式的微生物。

1 .But jarosite on Earth incorporates all kinds of microorganisms into its crystalline structure.

但是地球上的黄钾铁矾的晶体结构包含各种各样的微生物。

2 .So it's possible that if the jarosite on Mars was also formed with the help of microorganisms, we might be able to detect remnants of them in the samples we find.

所以,如果黄钾铁矾在火星上也是在微生物的帮助下形成的是有可能的,我们从找到的样品中也许可以检测到残余的（微生物）

3 .And we have instruments now that will enable us to try to do this.

我们现在的工具也将使我们能够这样做。

4 .For example, there's a new instrument called the microfabricated organic analyzer, or M.O.A. .

例如，有一个新仪器名为微加工有机分析仪，或M.O.A.。

1 .The organic analyzer is an amazing tool.

有机分析仪是一钟很了不起的工具。

2 .It will be able to collect soil samples and analyze them right there on Mars, pure, untouched samples.

它能够收集土壤样本，并且在火星上立刻进行分析，这样的样品纯净，没有被破坏。

3 .It will let us eliminate the risk we would take of contaminating the samples if they were brought back to Earth.

它使我们消除了将样品带回地球而被污染的风险。

4 .And what they'll look for specifically in the soil is amino acids.

他们要在土壤里找的东西就是氨基酸。氨基酸，

1 .Amino acids, as you may know, are the building blocks of proteins.

正如你可能已经知道的，是蛋白质的基石。

2 .In fact, there are twenty standard amino acids involved in making proteins and lots more that aren't.

实际上，有二十种标准的氨基酸可以制造蛋白质，而更多的氨基酸不能制造。

1 .And here's the important thing: amino acids are what we call handed.

这正是重要的东西。氨基酸我们叫做螺旋。

2 .They can exist in two forms, which are mirror images of each other like hands.

他们以两种形式存在，像双手一样一个是另一个的镜像。

3 .Right and left hands have the same number of fingers in the same order plus one thumb.

左手和右手有相同的手指数并以同样的顺序排列外加一个大拇指。

4 .But right and left hands are not the same. They are mirror images.

但是右手和左手又不是一样的；他们是镜像的

5 .Well, like hands, amino acids can be right or left-handed.

像手一样，氨基酸也有右旋和左旋。

6 .And the twenty that make up the proteins on Earth are all left-handed.

在地球上能够形成蛋白质的二十种氨基酸都是左旋的。

1 .Now, one reason the M.O.A. , the organic analyzer is so impressive is that it tests not just for the presence of amino acids but also for the handedness of amino acids.

如今，有机分析仪令人印象如此深刻的原因之一是他不仅能检测出氨基酸的存在还可以检测出氨基酸的旋的方式。

2 .If amino acids are found, it would be especially interesting if they show a prevalence of one type of handedness, either left, like amino acids on Earth, or right.

如果找到氨基酸，如果找到他们旋的方向，像在地球上的氨基酸一样向左，或是向右都是很有趣的。

3 .See, other physical processes in space, processes that don't involve living organisms,can create amino acids.

看，在太空中的其他的物理反应过程，这些过程不涉及生物，能够形成氨基酸

4 .But the ones synthesized through abiotic processes, which is to say not involving microorganisms, occur in equal numbers of right- and left-handed.

而且是通过非生物合成，也就是说不涉及微生物，发生了相同数量的右旋和左旋。

1 .So, a prevalence of left-handed amino acids would indicate they were biological in origin, which would be amazing!

因此，左旋氨基酸的普及表明他们生物起源，这将是惊人的！

2 .A prevalence of right-handed ones... well, that would be really amazing!

一个普遍的右旋的氨基酸。。。嗯，这真的是太棒了！！

3 .Because the organisms that created them would be unlike anything we have on Earth, which produce only left-handed ones.

因为创建了它们的起源将不同于与在地球上的我们找到的左旋的起源。