教程
....\lecture1
....\........\lecture1.ppt
....\lecture2
....\........\lecture2.ppt
....\lecture3
....\........\image1.jpg
....\........\image2.jpg
....\........\image3.jpg
....\........\image4.jpg
....\........\lecture3.ppt
....\........\pic2.ppt
....\........\picture.ppt
....\projgeom
....\........\projgeom
....\........\........\exam1.bmp
....\........\........\lineinfinity.bmp
....\........\........\planeinfinity.bmp
....\........\........\pointinfinity.bmp
....\........\........\projgeom.ppt