A.求和操作只能對(duì)同列的數(shù)據(jù)進(jìn)行
B.求和操作對(duì)同行同列的數(shù)據(jù)都能進(jìn)行
C.求和時(shí)要多選中一個(gè)空白格，以便保存和
D.求和操作只能對(duì)同行的數(shù)據(jù)進(jìn)行

A.對(duì)于每一個(gè)數(shù)據(jù)存儲(chǔ)，都應(yīng)該有流入的數(shù)據(jù)流和流出的數(shù)據(jù)流
B.離開(kāi)數(shù)據(jù)存儲(chǔ)的數(shù)據(jù)流表示對(duì)數(shù)據(jù)存儲(chǔ)的調(diào)用
C.流向數(shù)據(jù)存儲(chǔ)的數(shù)據(jù)流表示對(duì)數(shù)據(jù)存儲(chǔ)的修改
D.數(shù)據(jù)存儲(chǔ)可以存儲(chǔ)非電子文檔和文本文檔