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探索世界奥秘之Life Story(生命物语) Unit7
They haven't changed because their environment has stayed the same. The water they live in bubbles up from deep in the earth, and so it's always the same temperature. But just meters away the environment is very different, away from the thermal1 vents2 with the ebb3 and flow of the water, the temperature fluctuates. Billions of years ago, bacteria were living here too, but as their living conditions changed, they changed as well. From one generation to the next, there were minute alterations4. In themselves they were almost insignificant5, but these tiny changes started the most amazing process.
--Because if you add up enough tiny changes from generations through millions of generations, you can get a revolutionary transformation6.
From being simple bacteria the creatures in these pools became more complicated. Single cells became groups of cells, and groups of cells (became) early plants and animals, and the changes continued. Dozens of species became hundreds, and hundreds turned into tens of thousands. Parts of bodies were adapted to meet new challenges. Great leaps were made. A fish's fins7 over countless8 generations developed into legs and it became a reptile9. Some reptiles10 developed feathers and became birds. Others became mammals in every shape and size from blue whale to baboon11, every creature we see on the earth today including ourselves. All these happened. It's the miracle of evolution. The human body is just one branch in the huge spreading tree of life that grew from those simple bacteria.
Yet we carry with us the remnants of what has gone before us in our strange past, and there is a place we can go to see just one of those remnants, shaped by one of evolution's truly incredible transformations12. It's inside my own head. All we need to do is go and find it.
This is my eardrum, a thin skin stretched tight across my ear canal. But what I want to show you lies on the other side of my eardrum. This device can take me there. I'm inside a huge magnet with a field strong enough to lift a car clean off the ground. It's a magnetic resonant13 scanner and it can reveal layer by layer what's inside my head. Up to now, this has been the forefront of medical imaging, but we are about to take it one step further.
By putting the medical scans together, we've created a 3-dimensional picture of my own head and I can look at any part of it that I want.
words and expressions
thermal : Of, relating to, using, producing, or caused by heat.
热的:有关、用、产生热的或由热造成的
ebb and flow :潮的涨落,盛衰,消长
minute:Exceptionally small; tiny微小的, 异常小的,极细微的
baboon:狒狒
remnant:A surviving trace or vestige:
遗留下来的痕迹或者残余
eardrum:耳膜
field:magnetic field:磁场
resonant :Producing or exhibiting resonance:
共鸣的,共振的:产生或显示共鸣的
1 thermal | |
adj.热的,由热造成的;保暖的 | |
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2 vents | |
(气体、液体等进出的)孔、口( vent的名词复数 ); (鸟、鱼、爬行动物或小哺乳动物的)肛门; 大衣等的)衩口; 开衩 | |
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3 ebb | |
vi.衰退,减退;n.处于低潮,处于衰退状态 | |
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4 alterations | |
n.改动( alteration的名词复数 );更改;变化;改变 | |
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5 insignificant | |
adj.无关紧要的,可忽略的,无意义的 | |
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6 transformation | |
n.变化;改造;转变 | |
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7 fins | |
[医]散热片;鱼鳍;飞边;鸭掌 | |
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8 countless | |
adj.无数的,多得不计其数的 | |
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9 reptile | |
n.爬行动物;两栖动物 | |
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10 reptiles | |
n.爬行动物,爬虫( reptile的名词复数 ) | |
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11 baboon | |
n.狒狒 | |
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12 transformations | |
n.变化( transformation的名词复数 );转换;转换;变换 | |
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13 resonant | |
adj.(声音)洪亮的,共鸣的 | |
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