单词：crop roots do not always reach the C horizon
单词：crop roots do not always reach the C horizon 相关文章
Conditions on Mars were so harsh that it was hard to imagine any life surviving there. The idea of sophisticated aliens was wiped out. We know that conditions on Mars today are not very good for life.
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These discoveries raised the stakes. Here was a planet similar to our own. Mars might not have cities or civilizations. But it could be home to other smaller life forms like microbes. Chris McKay is N
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I think it is exciting. Because it would imply that if life arose independently on Mars. The implication is that life is pervasive throughout the universe. This is why Mars has so obsessed scientists.
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In 2001 a new NASA probe was launched. Called Odyssey, it was sent to Mars to carry out the most detailed analysis ever of the planet’s surface. What it has discovered may be about to answer one of
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But even if there had been water, life doesn't start overnight. Even a simple microbe is the product of complex chemical systems that take millions of years to evolve. Had the water lasted long enough
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Rice had seen the same thing in Iceland, one of the few places on Earth with similarities to Mars. It too is extremely cold, and most of the water is frozen into glaciers. And also like Mars, buried u
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For Mars to have rivers, it must once have had streams, rain, clouds and an atmosphere, a planet just like the Earth today-if these were rivers. They had to be sure. The answers would come in 1998 wit
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William Boynton is professor of planetary sciences at the University of Arizona. And he's dedicated his life to looking for water on Mars. The link between life and water is very strong. Even here in
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The hardest-hit state is Iowa, the leading corn state and last year's top soybean producer. Transcript of radio broadcast: 24 June 2008 This is the VOA Special English Agriculture Report. Farmers in parts of the American Midwest face a difficult rec
VOA慢速英语2008年（六）月
The Secret Life of Roots Plant roots are important to life on earth. Roots take in water and nutrients that the plant needs to live and grow. They also help secure plants in dirt to prevent erosion - the breakdown of soil by natural forces. Roots are
2015年VOA慢速英语(九)月
'Deepwater Horizon' Honors The Sacrifice Without Sacrificing The Action play pause stop mute unmute max volume 00:0003:02repeat repeat off Update Required To play the media you will need to either update your browser to a recent version or update you
2016年NPR美国国家公共电台10月
Johnny, looking out there. What do you see? field, some hay. No, its more than that, mate. Come on, now work with me here. What is it? Honestly man, I just see a field. It's a cosmic canvas. It's a blank supernatural sheet for extra terrestrial art.
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Of course, any terraforming is still a long way off. The next few expeditions to Mars will definitely be made by machines. NASA, are sending 2 rovers, capable of travelling over 100 meters a day in se
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Well, hearing that Odyssey had found subsurface water on Mars was enormously exciting for somebody who is involved in planning to send humans to Mars. Water has a number of important uses for us. At t
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Life on Earth is basically proteins and DNA, so we can wonder if there is life on Mars will also be DNA and proteins, the same type of DNA, the same type of proteins. One might think that DNA is such
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But there was something even better. Odyssey may not just have found ice. There may also be liquid water, and that means, there could be living creatures there too. Right now, there might be liquid wa
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But they never got there. The first disappeared into deep space. Another missed its target when its coordinates were confused. One NASA control center was working in metric, the other in feet and inch
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The ground here is permafrost, a mixture of soil and ice frozen together. A group of Russian scientists have teamed up with NASA to drill down into it in search of microorganisms. It's work that's bee
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One of these wavelengths corresponds to hydrogen, another wavelength would be iron. Another wavelength would be oxygen. And so you go to the part of the spectrum you are interested in and you see you'
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By Brian Wagner Miami 14 May 2008 As crop prices remain high, farmers and other landowners are working to expand their output and take advantage of big profits for wheat, corn and soybeans. The boom is creating pressure to begin farming on lands enro
VOA标准英语2008年（五月）