A、<span style="font-family: 楷体; font-size: 19px; text-indent: 37px;">社会功能 </span>
B、<span style="font-family: 楷体; font-size: 19px; text-indent: 37px;">增值优化功能</span>
C、<span style="font-family: 楷体; font-size: 19px; text-indent: 37px;">检索功能</span>
D、<span style="font-family: 楷体; font-size: 19px; text-indent: 37px;">存储功能</span>