说明：  vb编写的arcengine二次开发实例，不仅包括了arcgis二次开发的一些基本功能，更有一些高级开发功能，如空间分析，三维分析等等
(vb examples prepared arcengine secondary development, including not only the arcgis secondary development of some of the basic functions, and some advanced development features such as spatial analysis, three-dimensional analysis, and so)