1 expressions and control flow
2 a way of abstraction: variable, function
3 a way of combination:function, object,data
In object-oriented language, we use objects to combine.
In process-oriented programming langugae, we use data to combine.
In function programming language ,we use function to combine
Three elements of programming language
原文：http://www.cnblogs.com/zhaodonglin/p/5159642.html