VC++ 利用窗口化命令打开、关闭光驱，好像只能用一次，也就是第一次打开是有效的，再次打开就没有用了，仔细研究一下吧。-VC++ use windowing commands to open and close the CD-ROM drive, seems to only be used once, which is open for the first time to be effective, turn it on again there is no use, a closer look at it.