首先，他们必须搞清楚火星上是否曾经存在过生命。
To begin with, they will have to find out whether life has ever existed on the planet of Mars in the past.
不幸的是，从考古学证据的性质来看，这类人物总是难以捉摸的，因为考古学证据几乎是一成不变的，只是曾经存在过的东西的一种样品。
Unfortunately, it is in the nature of the archaeological evidence, which is almost invariable only a sample of what once existed, that such figures will always be elusive.
由于自然选择，大多数曾经存在过的物种已经灭绝，所以这不是一个新现象。
Thanks to natural selection, most species that have ever lived has already gone extinct, so this is not a new phenomenon.
这更容易让人相信它们曾经存在过。
据说她看起来非常像曾经存在过的雷龙。
She is reputed to look very much reminiscent of the Brontosaurus.
这些生物也许是之前曾经存在过的生物的一部分。
These creatures would be the remnants of the previous inhabitants.
只要痛楚提醒着我他曾经存在过，你们都曾经存在过。
The pain is my only reminder that he was real, that you all were.
大多数古代的泥炭森林都逐渐消失，只留下曾经存在过的零星证据。
Most ancient peat forests die gradually, leaving only spotty evidence of what grew there.
科学家称：这些证据毫无疑问地证明火星上曾经存在过水。
Scientists said the new evidence proved beyond doubt that water has been existed on Mars.
这一发现不仅显示了地球上可能存在其他类型的生命，或者曾经存在过。
The finding not only presents the possibility that alternative life forms can exist, or once existed, on Earth.
在数十亿曾经存在过的人中，没有一个人的心跳是和你完全一样的，这是不可思议的。
It's amazing that out of all the billions of people who've ever lived, no one has ever had a heartbeat exactly like yours.
但是，在这个时期，党内也曾经存在过另一种偏向，就是分散主义的偏向。
However during this period another kind of deviation developed within the party namely decentralism.
在我死后一年，谁会还记得我面孔，记得这个世界上还曾经存在过这么一个人。
After my death one year, who will remember my face, remember that this world has ever existed, so a person.
铁幕在当时并没有完全被打破，但是那个晚上，任何小步走的可能性就不复存在了，即使曾经存在过。
The Iron Curtain did not unravel at that moment, but that night the possibility of cautious, incremental change ceased to exist, if it had ever really existed at all.
家长们的教育手法也在不断变化，“虎妈妈”，即使她曾经存在过，现在也比以前温和多了。
Here, as elsewhere, parenting practices are always changing — the Tiger Mother, if she ever existed, is not as fierce as she once was.
如果你只是想掴共同的博客，写一些东西来把它，然后忘记它曾经存在过，你可能最好的坚持与项目发薪。
If you just want to slap a blog together, write a few things to put on it, and then forget it ever existed, you're probably best sticking with Project Payday.
既然高等生命能够在地球上形成，那么这项发现也可以佐证，在更加温暖潮湿的火星或者寒冷缺氧的金星上曾经存在过生命。
While giving insights on how higher life may have formed on Earth, the finding may also bolster the theory that life may have once existed on a warmer, wetter Mars or a cooler, clearer Venus.
我知道我不是曾经的那个我，但有一件事对我的打击很大：我的家人，那些我最亲爱的人们，甚至都不知道真正的那个我曾经存在过。
I knew I was not the person I once was, and it struck me that the people in my home, the ones I loved the most, had no idea that such a person had ever even existed.
无论曾经生活在这些壳里的生命是什么它们都已经永远的消失了，但这里总是有一些它们曾经存在过的痕迹——那些与其说是我们偶尔打扰到粘糊糊的软体动物，倒不如看成更具奇异可爱特质的小东西。
Whatever lived in these shells has long since disappeared, but there is still a sense of previous occupation—by something perhaps more exotic and lovely than the slimy mollusk we occasionally disturb.
因此，如果它曾经在地球上存在过，那么它在很久以前就应该衰变了。
Therefore, if that ever had been present on Earth, it would have decayed ages ago.
历史的星空有群星闪耀，在浩如烟海的人类文明史上，曾经有这么一群英雄存在过。
History of the sky of stars, in the vast human's civilization, once existed have so a group of heroes.
编辑并没有对内容的真实性进行报怨，而且实际上，并不能证明所谓的作者曾经实际存在过。
The Editor makes no claim to the factuality of the content, and in fact, cannot prove that the alleged author actually ever existed.
没有人会从自己的过去里逃脱出来，不仅仅是因为它曾经真真正正的在某段时间存在过，还因为它至今依然存在人们的内心了。
Nobody will extricate himself from the past , not only because it has ever existed for a certain time , but also because it still exist in one's mind.
霍布斯如何形容自然的状态？他说他不相信它曾经“普遍地”存在过，但类似的东西现今存在于国与国间的关系。
How does Hobbes describe the state of nature? He says that he does not believe that it ever existed "generally", but something like it exists now in the relation between nations.
土族民族狩猎野牛，这是一种曾经在美洲平原上大量存在过的一种野生动物。
They hunted bison, a type of wild animals which used to exist in huge numbers on the plains of America.
土族民族狩猎野牛，这是一种曾经在美洲平原上大量存在过的一种野生动物。
They hunted bison, a type of wild animals which used to exist in huge numbers on the plains of America.
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