说明： com和exe都是可执行文件，但似乎人们对exe更熟悉 ，其实com的功能也是相当强大的 ，要了解WINDows，就必须了解com (com and exe are executable files, but it seems people are more familiar with the exe. in fact com function is quite strong, to understand WINDows, it is imperative to understand com)
