例如，亚里斯多德在公元前三世纪曾有一个研究型图书馆。

For example, Aristotle once had a research library in the third century B.C..

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并于公元前三世纪成型。

The wall finally took shape in the the third century B.C.

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并于公元前三世纪成型。

The wall finally took shape in the the third century B.C.

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