北大青鸟C#课件系列，从c#基本语法讲起、逐渐深入提高，每张课件中还有一些课堂练习以及练习解答和源代码。非常不错的c#课件，图文并茂，清楚易懂。-Beida Jade Bird C# courseware series, I start from the basic syntax of c#, and gradually improve the depth, each courseware, classroom exercises, and practice answers and source