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The first significant civilizations of europe formed in the second millennium bc .

欧洲第一个重要的文明出现在公元前第二世纪。

The horse collar arrived in the third century bc , in china .

马颈轭第一次出现在公元前3世纪的中国。

The city-states of greece became a province of the roman empire in 27 bc .

在公元前27年，希腊城邦沦为罗马帝国的一个省。

The chinese developed a lodestone compass to indicate direction sometime in the 4th century bc .

公元前4世纪，中国人造出了一个天然磁石罗盘来提示方向。

The clearest explanation of this extraordinary modern phenomenon comes from a doctor who lived in the 5th century bc .

这个当代非同寻常的现象最清楚的解释却来自于一位生活在公元前五世纪的医生。