教育学习   常速英语

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SPEAKER 1: Two groups of animals are defined as different species when individuals from one group don't mate and reproduce with those from the other. One way a species can split into two is for pop...

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[SAWYERS:] BCR-ABL is a kinase. I want you to watch it change. It's flipping back and forth from an active to an inactive conformation. Now, we're looking at the skeleton and you see that lo...

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ANDREW BERRY: Evolution by natural selection. This is an idea that has been sought after since the dawn of human thought. And it was a theory that was discovered by two people, and we've...

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The malaria parasite is an ancient organism. It has been with us since before we were human. Famous victims include Alexander the Great Genghis Khan and George, Washington. The malaria lifecy...

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[NARRATOR:] Mosquitoes are usually vegetarian, preferring to drink nectar, fruit juices, and honeydew. Only a pregnant mosquito will bite humans, seeking nutrients from blood to nourish he...

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SEAN CARROLL: For tens of thousands of years, much of North America lay buried under ice up to a mile thick. Then the massive ice sheets receded. In what is now Alaska, ocean bound stream...

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So the basic concept is that heat inside the Earth drives motions. We have convection currents, through which heat is dissipated from the interior of the Earth. Those convection current...

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TYLER LYSON: Even though I've collected thousands and thousands of dinosaur bones and other fossils, every fossil that I find, it's just quite a thrill because you're the first person ...