public declare function beep lib "kernel32" alias "beep" (byval dwfreq as long, byval dwduration as long) as long
'返回值:rue(非零)表示成功,否则返回零。会设置getlasterror
'dwfreq --------- long,声音频率(从37hz到32767hz)。在windows95中忽略
'dwduration ----- long,声音的持续时间,以毫秒为单位。如为-1,表示一直播放声音,直到再次调用该函数为止。在windows95中会被忽略