Large public activity has the character of big population density and strong fluidity, which is liable to safety accident and causes big casualties and social impacts.

大型公共活动人口密度大、流动性强，极易引发安全事故，造成大量人员伤亡和恶劣社会影响。

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Since1995, Beijing Science and Technology Week has been held13 times as a large public science popularization activity.

北京科技周作为一项大型公益性科普活动，自1995年举办以来，今年已经是第13届了。

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The activity will become the most rewarding large public welfare party in the field of youth public welfare in 2011.

整个活动成为2011年青年公益领域最有收获的大型纯公益聚会。

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To the extent the federal money is spent on needed highways and bridges, or other items that serve the public at large and thereby reduces the barriers to doing business, there is at least the prospect of additional economic activity.

FORBES: The Left's Grip On The American Economy