A 2007 survey by the Computer Security Institute found that 50 percent of respondents had a laptop or other mobile device sto-len in the past year.

一份计算机安全研究协会2007年的调查发现，有50%的受访者在过去的一年里有笔记本电脑或其他移动设备被偷。

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More than 50 ancient forts have been identified along its length, established to maintain security and levy taxes.

沿途已确定有50多台名古炮台，它们建立用来维持安全和征税。

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"It has been a cornerstone of the security of both nations, as well as the economic prosperity of both nations for almost 50 years now,".

VOA: standard.2009.09.23

Bottom line: About two-thirds of retirees already rely on Social Security for 50% or more of their income, and that figure appears bound to rise.

FORBES: Magazine Article

Meanwhile, at an Indiana middle school, security cameras captured 50 students taking part in a gigantic food fight.

NPR: Troubled Classrooms... and Cafeterias

When the 1977 payroll-tax increase passed Congress, legislators congratulated themselves on having assured the financial solvency of Social Security for the next 50 years.

CNN: A Debt-Threatened Dream