Scientists have advanced many theories about why human beings cry tears.

关于人类为什么哭的时候会流泪，科学家已经提出了很多理论。

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Scientists have advanced many theories about why human beings cry tears, none of which has been proved.

科学家提出了许多关于人类为什么哭的理论，但没有一个得到证实。

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The reason why we should learn foreign languages is that they have become a vehicle for bringing in advanced ideas, science and technology.

我们之所以要学习外语，是因为它们已成为引进先进思想和科学技术的媒介。

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And that is why advanced navies such as Britain's and America's are now among the most enthusiastic and earliest adopters of electric-drive ships.

ECONOMIST: Electric ships

So why are these advanced Gallic palates not being put to use for coffee?

BBC: The Paris coffee revolution

One of the reasons why I started Advanced Style is I saw so many of my friends wearing vintage clothing, so I think young girls still kind of have that desire to be that glamorous woman.

FORBES: Advanced Style: A Word About Fashion After 50