http://www.cnblogs.com/jesse2013/category/530647.html
http://www.cnblogs.com/Terrylee/category/48778.html
http://www.cnblogs.com/coolcode/tag/%E8%A1%A8%E8%BE%BE%E5%BC%8F%E6%A0%91/
表达式树系列
原文：http://www.cnblogs.com/qixuejia/p/5035085.html
