为什么我不能挂载光驱呢？

xwq_007

[root@xwqflash quickmouse]# mount -t iso9660 /dev/hdb /mnt/cdrom
mount: block device /dev/hdb is write-protected, mounting read-only
mount: /dev/hdb already mounted or /mnt/cdrom busy
mount: according to mtab, /dev/hdb is already mounted on /mnt/cdrom
[root@xwqflash quickmouse]#