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A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Sun's very center. It is here that is to be found the source of the energy that the Sun constantly pours out into space as light and h
英语小短文
A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Sun's very center. It is here that is to be found the source of the energy that the
新东方背诵文选
The source of Energy A summary of the physical and chemical nature of life must begin, not on the Earth, but in the Sun; in fact, at the Sun's very center. It is here that is to be found the source of the energy that the Sun constantly pours out into
英语小短文
Questions 12-20 The elements other than hydrogen and helium exist In such small quantities that it is accurate to say that the universe somewhat more than 25 percent helium by weight and somewhat less than 25 percent hydrogen. Astronomers have measur
托福英语
Let's begin by winding the timeline back 13.7 billion years, to the beginning of time. 让我们把时间往回拨到137亿年前，也就是时间的开始。 Around us, there's nothing. There's not even time or space. 四周是什么也没有，根本
TED演讲教育篇
What makes the sun shine? For a lot of folks, this is the kind of thing that doesn't even require explanation: it just does. But just being a commonplace phenomenon in no way explains it. Something must cause the sun to shine. And, in fact, there is
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