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A calf is a young cow. A young female cow, especially one that has not yet had a calf, is called a heifer: H-E-I-F-E-R.
VOA: special.2009.07.21
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He urged revival of the slave-trade in the late 1850s, and he developed a theory of what he called warranteeism--w-a-r-r-a-n-t-e-e-I-s-m.
他促成了十八世纪五十年代后期,奴隶交易的复苏,还自己发明了一套理论,名为抵押品主义
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I remember there was a toy store in my town. It was just Toys R us.
我记得我们城镇有一个玩具店，就是"Toys R us".
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When I was a young child in school, I had to learn the three R's.
VOA: special.2009.07.26
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I'm glad to hear that no one counted this r equal zero as a node.
我很高兴没听到有人把ｒ等于０这处也算作是一个节点。
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And this one, I was skiing out in Salt Lake City and the name of a building out there was Reid with R-E-I-D and it sounded good at the time."
VOA: special.2009.07.06
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And at a distance of 2 r naught, I have a positive repulsive term.
在这2r圈的距离上，这里有一个不可忽略的排斥场。
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What we do is we take the interest rate, which I'll call r, and plug it into a formula, which I didn't actually do the arithmetic to their number.
我们只需将利率r,代入等式中,虽然我没有代入数字验证过...
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If you want to write it as a vector equation, you want to write it as v square over r minus-- I want to say that it's pointing in the direction toward the center.
如果要写出矢量方程,就应该写成 -v^2 / r,也就是说,方向就向圆心
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So I have a distance here of 2 r naught.
因为有一个2r圈的距离。
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But instead in this chemistry course, I will just tell you the solutions to differential equations. And what we can do is we can start with some initial value of r, and here I write r being ten angstroms. That's a good approximation when we're talking about atoms because that's about the size of and atom.
但在这个课里，我会直接，告诉你们微分方程的解,我们可以给距离r一个初始值,我这里把r取10埃,当我们讨论原子时,这是一个很好的近似,因为原子的尺寸。
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So, for example, if I have a sodium ion over here, and I have a chloride ion over here, where the distance from center to center r I'm denoting as r, this is nucleus to nucleus separation.
所以，比如这有一个钠离子，和一个氯离子，它们中心与中心间的距离,我把它设为，这是原子核和原子和的间距。
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If you are describing a particle with location R, the vector we use typically to locate a particle, R then R is just i times x + j times y, because you all know that's x and that's y.
如果你要描述一个位移为 R 的质点,这个矢量一般用表示质点 R 的位移,R 可表示为 i ? x + j ? y,显然你们都知道这段是 x,那段是 y
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That was Cartesian space. When I plot r as a distance out from the nucleus that is sort of our simple-minded planetary model. Now let's look at energy.
笛卡尔坐标系，当我用r表示,离原子核的距离时，那只是我们头脑中简单的,类似行星的模型，现在我们看一下能量问题。
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r+ And let's say that sodium has a radius, r plus, r- and chlorine has a radius, r minus, when r is very large in comparison to the radii of the ions, I don't need to draw them this way.
让我们假设钠有半径，是，氯也有半径，是，当r比离子半径大很多的时候，我不需要这样来描述。
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