社会科学家是如何挑战家庭的传统定义的?

The security of our personal information is getting worse and worse.

语法上没错.
不过感觉上用fragile形容身体上的虚弱更好,weak在这里感觉更加像是能力上的.
The old man was found fragile.
The old man was found physically challenged.（这种说法比较含蓄,就是所谓的"political correctness")

之前刚写了一篇中美09年经济展望的论文,巧了.
Chinese economic outlook for 2009
From my point of view,generally speaking,china would forced to face many challenges in 2009 due to the undertaking recession issues,but in the global economic world,it would still be expected to act as one of the first countries to get recovered from the recession.
There are five major issues regards to Chinese economic condition in 2009.First,China will be challenged by the influence from international economic crisis.Secondly,due to the combination impact from the home and abroad,the macroeconomic regulation in China would become more complicated; in another word,it may result in a repeating domestic inflation and deflation.Thirdly,the above situations might have side-effects on Chinese stock market and real estate market; further,the small and medium companies might face serious liquidation issues.In Addition,there is a great possibility of a dramatic decline on the employment rate.Last but not least,it would become tremendous difficulty for government to maintain a balanced financial status and also inject further confidence into Chinese economic.
To sum up,from the above analysis,it is clear that the economic situation in China for 2009 is not in positive.However,with more focus on Chinese domestic market and increasing living allowances of our lower-income groups,it is possible to achieve a stabilized economic and social position even in such a serious condition.