在多媒体中记录音乐的文件格式常用的有WAVE、MP3和MIDI等。其中WAVE记录了音乐的(61)，MP3记录了(62)的音乐，MIDI记录了(63)。在用MPEG格式存储的图像序列中，不能随机恢复一幅图像的原因是它使用了(64)技术，影响这种图像数据压缩比的主要因素是(65)。

(89)

(88)

(86)

(87)

(84)

User　programs　interact　with　the　kernel　through　a　set　of　standard(71).　They　request　services　to　be　provided　by　the　kernel.　Such　services　would　include　accessing　a　file:　open　close,　read,　write,　link,　or　execute　a　file;　starting　or(72)accounting　records;　changing　ownership　of　a　file　or(73);　changing　to　a　new　directory;　creating,(74),　or　killing　a　process;　enabling　access　to　hardware　devices;　and　setting　limits　on　system　resources.　Unix　is　a　multi　-user,　multi　-tasking　operating　system.　You　can　have　many　users　logged　into　a　system　simultaneously,　each　running　many　programs.　It's　the　kernel's　job　to　keep　each　process　and　user　separate　and　to　regulate　access　to(75),　including　cpu,　memory,　disk　and　other　L/O　devices.

(83)

(82)

(81)

(79)