继续发关于ＤＤＳ的文档，可以在多篇比较之下看出真正的核心是什么，我觉得这样更好，如果需要其他的我还有，可以联系-to the DDS on the documents, in more than to see the real comparison is the core of what I think this better, if I need to have other, can be linked