鉴于穴居人一般都居住在洞口附近，因此，拉斯科岩洞许多代穴居者隐藏他们的艺术作品，其中必定存在某些原因。

Since cave dwellers normally lived close to entrances, there must have been some reason why so many generations of Lascaux cave dwellers hid their art.

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“下降的原因之一是20世纪80年代的经济形势。”苏塞克斯大学的亚历山大·莫拉迪说。

"One reason for these decreases in height is the economic situation in the 1980s," said Alexander Moradi of the University of Sussex.

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游客人数的增加是该市人口从20世纪50年代的17.5万人下降到目前人数的一个关键原因。

The tourist increase is one key reason the city's population is down from 175,000 in the 1950s.

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