Dictionary<TKey, TValue> Class
http://msdn.microsoft.com/zh-tw/library/xfhwa508(v=vs.100).aspx
http://msdn.microsoft.com/zh-tw/library/bb347013(v=vs.100).aspx
http://social.msdn.microsoft.com/Forums/en-US/926c2d0c-f7e3-48ff-ac86-28901ad18fc0/how-to-get-value-by-key-in-dictionary?forum=csharplanguage
http://stackoverflow.com/questions/12169443/get-dictionary-value-by-key
http://www.dotblogs.com.tw/puma/archive/2008/10/17/5711.aspx
JoneyLiu 