A.載體損害B.設(shè)備損壞C.操作失誤D.程序缺陷
A.1B.2C.3D.4
A.檔案目錄數(shù)據(jù)庫 B.檔案全文數(shù)據(jù)庫 C.多媒體數(shù)據(jù)庫 D.流媒體數(shù)據(jù)庫