一个关于引用的问题 程序编译过程中出现这样一个警告:the primary reference "system.core.version=3.5.0.0,,cculture = neutral,publick token = ....",which is a framework assembly,could nmot be resolved in the current target framework,.netFramework, version = v4.0. to resolve this problem,either remove the reference or target your application to a framwork version which contains "system.core,version = 3.5.0.0,culture= .."