单项选择题某磁盘盘组共有10个盘面，每个盘面上有100个磁道，每个磁道有32个扇区，假定物理块的大小为2个扇区，分配以物理块为单位。若使用位图管理磁盘空间，则位图需要占用（1）字节空间。若采用空白文件管理磁盘空间，且空白文件目录的每个表项占用5个字节，则当空白文件数目大于（2）时，空白文件目录占用的字节数大于位图占用的字节数。
单项选择题
VRML is a（1）for 3D multimedia and shared virtual worlds on the WWW.In comparison to HTML, VRML adds the next level of interaction,structured graphics,andextra（2）（z and time）to the presentation of documents.The applications of VRMLare（3）,ranging from simple business graphics to entertaining WWW page graphics, manufacturing,scientific,entertainment,and educational applications,and 3D shared virtual worlds and communities. X3D is the name under wluch the development of VRML is continueD.X3D is based on XML andis backwards（4）with VRML.Furthermore,it is componentized,profiled, and extensible,which makes it possible to use X3D in very different（5）,from high-end visualizations to lightweight applications.
