单词：railway security
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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
This is Scientific American's 60-Second Science. Im Cynthia Graber. This will just take a minute. One of the problems with large-scale solar power plants is that they require a huge amount of space. To rise above that problem Israeli researchers rece
Scientific American(三)月
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
Over the lights of sunset and vine We're floating away From the fortune and fame And your lips are mine They're raspberry wine Your body's a map I will follow into the sky Cause what you got Is all that I want It's all that I want And still that's no
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